diff --git a/2020/18/input b/2020/18/input
new file mode 100644
index 0000000..5746c1f
--- /dev/null
+++ b/2020/18/input
@@ -0,0 +1,373 @@
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+(4 + (9 * 9) + (4 + 4 * 6) * 5 * (9 + 2)) * 3 + 9
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+(4 * 5 * 8 + 3 * 2) + 2 + (7 + 2 + 3 * 7 + 6 + 7) * 5
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+6 * 3 * 9 + (7 * (6 * 5 + 2 + 7))
+5 + 8 * (3 + 5 * (6 * 9 + 5 + 9 + 5))
+4 * 7 * 8 * (4 * (7 + 2 + 7 * 8 + 6 + 6) * 6 + 3)
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+3 + 7 * 5 * 3 * (9 * 4) + 6
+(6 * 8 * 9 + 6 + 5) * 9 + 5 * 4 * 7
+9 + 4
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+(9 * (3 * 8 * 9 * 8 + 7)) * 3 + 2 + 2
+(4 + 3 * 7 * (9 + 9)) + 5 + 9
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+(8 * (3 + 2 * 4 * 4 + 4 * 2) + 2 + 8 + (7 * 3 * 6 * 6 + 5 + 9) * 9) + 5 + 7 * 9
+(5 * 3) + 3 * 2
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+9 + ((6 + 2 * 9 * 2) * (7 * 4 * 6 + 3 * 7) + 5 + 9) + (5 + (5 * 4 * 5 * 8 + 8) + 5 * (3 * 2 * 2 + 4 + 3 * 4))
+(6 * (8 + 9 + 3 * 3)) + 7 * 6 * 4 + (9 + 4 * 2) + 4
+((2 + 2) + (8 * 7 * 6 + 4 * 2 + 6) + 3 + (5 + 8 + 2) * 2) + 6 * 9 + 2
+(3 + 6 + 7 * 2) * 9 + (4 * 9 + (2 + 6 + 4) + 4) + 6 + 9
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+(9 * 3) + 9
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+5 * (5 + 9 * (8 * 4)) * (7 * 6 * 8) + 2 + 3
+9 * 5
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+(6 * 4 * 7 * 3 + 7) + 5 * (8 * 4 * (4 + 8 * 4) * 9 * 2 * 3) + 9 + 9 * 2
+(8 * 4) + (5 * 4 + 4 * 4) * ((5 * 4 * 3 + 8) * 8 * 3 * 3 * 9 * 5) + 3 * (4 * 9 * 6)
+8 * 4 * 6 + 2
+(7 + 2 + 3 * (8 + 3)) + 2 + 9 * (2 * 2 * (4 + 6 * 6 + 3 * 2 * 8) + 7 + 7) + 8 * 7
+3 * (6 + 4 * (5 * 4 + 5 * 4 * 5 * 2) * (5 * 4) + 9) + 4 + 6 + 4 * (5 + 6 * (2 * 7 + 6 + 2))
+9 + 8 + (3 * 6 + 7 + 8 * 9 * 4) * 8 * 9 * ((3 * 8 * 8 + 9 * 7 + 6) * 4 * 2 + (2 * 2 + 4 * 3) + (6 * 6 + 9 + 9 + 8) * (8 + 8 * 4))
+5 + (7 * 6 * 6 * (3 * 2 * 3 * 6 * 7 + 7) * 7)
+9 * 9 + 3 * ((7 * 6 + 5 + 4) * 8 * (7 * 8 + 5 * 8) * (4 + 4 + 8 * 8 * 7 * 7) + 3 + 8) * 6
+2 * ((4 + 2 * 9) * (8 * 3) * 7 + 9) * 6 * 5
+(3 * (7 + 7 * 2 + 9) + (3 + 8) * 5 * (2 * 4 + 5 + 6 * 9) * 2) + 5 + 8
+2 * (2 + 8 + 5 * 6) * 2 + 7
+7 + (6 + 3 + 5 * 6 + 7 * 2)
+4 + 2 * 3 * (6 + 3 + 5 * 4 + 2) * 9 * (8 * 7 * 5 * 8)
+5 + (4 * 2 * 4 + 3 + 7 + 5) * 7 + 7
+8 + 2 + 4 + 7 + 2
+9 + 4 * 7
+6 + 5 * (5 + 9 * 7 * 6 * 5 + 7) * (7 + (6 * 9 * 7 + 5 + 6 * 4) + (9 * 9 + 7 * 9)) * 4 + 5
+7 * 7 * (8 * 3 * 3 + 9) + ((2 + 2) + 7 * 7 + 7 + 7 + 3) * 8
+2 + (4 * 7 * (7 * 5 * 4 + 5 + 5 + 5) + 7) + 5 + (6 + (9 + 6 + 6 * 3 + 3 + 5) * 2 * 9 + (3 * 7 * 5 + 5)) * (5 * 4 * 2 * 6) * ((7 + 4 + 7 * 2) * 7 + (5 + 7 * 7 * 3 * 4) * 8)
+((3 + 4) * (9 + 5 * 7 + 5 * 7 + 5) * 4) * 6 * 4 + 9
+(6 * 9 + 5 + (6 + 8 * 8 * 6 + 6) + 6 + 7) + 7 + 5 * 2 + 2
+8 * (7 * 4 + 5) * 8
+5 + 8 + 9 + (6 + 8) + (6 + 4 * 4 * 4 * 5 + 5) * 5
+4 * 6 * 9 + 8 * (2 * 5 + 2 * (6 * 2 + 4 + 7 * 6 * 2)) * ((7 * 3 + 6) + (2 * 9 * 6 * 8 * 5 + 6) + (8 + 8 * 2 * 9 * 7 + 2) + 8 * 7)
+4 + 4 + 7 + 5 + 2
+3 + (8 * 2 * 4) * 8 * (2 + (8 * 5 + 3 * 4 + 4)) * (2 * (5 * 6))
+7 + 8 + 7 + (2 * 7 * 7 * (9 * 8) * 5)
+5 + 7 + 9 + 4 * (8 + 6 + 9 * (3 + 9 * 3 + 5 * 3) * 5 + 4) + (8 * (3 * 8))
+4 * 2 * ((8 + 8 + 4) * (9 + 9) * 5 * 4 + 5 * 9) * 2
+4 + 3 * 4 * 4 * 6
+4 + 8 * (5 + 2 * 3 * 8 * 6 * 9) + 6
+2 + 7 * (8 * 4 * 8 * 2 * 8 + 6) + 7 + 2
+5 + 3 + ((8 + 3) * 6 + (6 * 2 * 9 * 8 * 8 + 3) + 8 * 2 * 7) + 9 + 3 * ((4 + 9 * 5) * 3 * 4 * 3 * 2 + 9)
+7 + (8 + (5 + 6 * 4 * 5 + 4 + 2) + (4 * 2) + 3 * 5 + 9) * 5 + 6 * 6
+7 + 3 * (9 + 3 + 5 + 2) * 9
+8 * 3 + (9 * (4 * 3 * 4) * 6 + 4 * 7) + 5 * 5 + (4 + 5 * (3 * 4 * 8 + 2 + 3 + 2))
+(7 * 2 * (7 + 8 * 4 + 7)) * 9 + 5 + 9
+4 * 7 * 5 + 3 * 5
+9 * 4 * 4 + 2 * (7 * (7 + 8 * 6 * 9 * 4) + (8 + 2) * 3 + 9 + 5) + 2
+8 * 7 * 5 + ((5 + 7 + 8 + 4 + 7) + 7 * (9 * 2 + 2) + 9) + 6
+5 + 4 + (4 + 5 * 5 * 2)
+6 + 7 * 2
+9 + (5 + 6 * (3 + 3 * 4 + 3 * 4) * 4 * (8 * 2 + 6 + 6)) * 3 * 3 + 3 + 4
+((3 + 6) * 8 * 5 + 8 * 2 * 9) * (4 * 7 + (5 + 6 + 5 + 9 + 4)) + ((5 + 6 * 3 + 2 * 8 * 3) + 2 + 9 + 7) + ((6 + 5 * 5 * 2 + 7) * 9) * 7
+2 + 3 + 6 * (4 + 2 + 8) * ((2 * 8 + 4) + (2 + 3 + 3 + 8))
+(6 * 2) + 5 * 9 + 2 + ((5 * 7 + 4) * (7 + 4 + 4) * 2 * 7 + (5 + 7 * 2 + 3 + 5) + (6 + 4 + 2)) * 6
+4 + (5 * 3 * (6 * 7 * 8 * 4 + 5) * 3) + 2 * 7
+((4 + 7 * 9) * 3) + 9 * (6 + 3 + 8 + 2)
+4 * 2 + 2 * (9 + 9 * 3 + (9 + 7 * 3 * 3 + 4 + 7) + (8 + 5) + 8) + 8
+5 + (8 * 4 + 9) * 2 + 2 * 2 * 5
+(5 * 8 * 3 * 5 + (3 * 2 + 9 * 5) * 6) + 5 + 8 + 3 * 2
+8 * (2 * (4 + 6 * 3 * 6 * 2 * 2) * (7 + 4 * 9 + 3) + 9)
+6 * ((4 * 3) * 6 * (5 * 5 * 6 + 6) + (3 * 2) * 5 * 3)
+8 + (3 * 6 + 4 + 9) * 2
+2 * 8 * 4 * ((3 * 3 + 9 * 7 * 5) * 7) + 2
+(6 + 9 * 2 + 4) * 4 * 4 * 3 + 6 * 8
+2 * 7 * 7 + (3 * 8 + 5) + 5 + 7
+3 + (9 * 2 + 6 + (4 + 8 + 9 * 5) * 4) * 8
+9 * (7 + 8)
+8 * (7 + 8 + (5 + 5 * 8) + 7 + 3) + 6
+(4 + 2 + 7 * 5) * 9 * 3 + 8 + 7 + ((9 * 4 * 4) + 4 * (6 * 3 * 3 * 6))
+(2 * 8 + (8 + 4 * 9 * 6 * 2) * 7) * 9 * 6 * 5
+9 + 7 + (4 + 5 + 6 + 3) + 3 * 6
+(8 * 2) + 4 + 3 + 7 * 2
+(4 * 4 + 4) + 8
+6 + 4 + 8
+3 * (5 + (2 * 6 * 5 + 7 * 6) + 7 * 2 * 8 * 8) + 8 * 4
+8 * 7 * (3 * 4 + 6 + 2 * 9 + 9) * 3 + (3 + 5)
diff --git a/2020/18/solution1.py b/2020/18/solution1.py
new file mode 100644
index 0000000..50669cc
--- /dev/null
+++ b/2020/18/solution1.py
@@ -0,0 +1,61 @@
+import re
+
+example1 = '1 + 2 * 3 + 4 * 5 + 6'
+example2 = '1 + (2 * 3) + (4 * (5 + 6))'
+example3 = '2 * 3 + (4 * 5)'
+example4 = '5 + (8 * 3 + 9 + 3 * 4 * 3)'
+example5 = '5 * 9 * (7 * 3 * 3 + 9 * 3 + (8 + 6 * 4))'
+example6 = '((2 + 4 * 9) * (6 + 9 * 8 + 6) + 6) + 2 + 4 * 2'
+
+with open('input') as f:
+    expressions = f.readlines()
+
+
+def calc(op, a, b):
+    if op == '+':
+        return a + b
+    elif op == '*':
+        return a * b
+    else:
+        raise Exception(f'Operator "{op}" not known')
+
+
+def solve(line):
+    num_stack = [0]
+    op_stack = ['+']
+
+    for char in line:
+        if char in [' ', '\n']:
+            continue
+
+        if char == '(':
+            num_stack.append(0)
+            op_stack.append('+')
+        elif char == ')':
+            op = op_stack.pop()
+            a = num_stack.pop()
+            b = num_stack.pop()
+            num_stack.append(calc(op, a, b))
+        elif char in ['+', '*']:
+            op_stack.append(char)
+        elif re.match('[0-9]', char):
+            num = int(char)
+            num_stack.append(int(char))
+            op = op_stack.pop()
+            a = num_stack.pop()
+            b = num_stack.pop()
+            num_stack.append(calc(op, a, b))
+
+        # print(num_stack, op_stack)
+    return num_stack.pop()
+
+
+print(example1, '=', solve(example1))
+print(example2, '=', solve(example2))
+print(example3, '=', solve(example3))
+print(example4, '=', solve(example4))
+print(example5, '=', solve(example5))
+print(example6, '=', solve(example6))
+
+print('Solution')
+print(sum(map(solve, expressions)))
diff --git a/2020/18/solution2.py b/2020/18/solution2.py
new file mode 100644
index 0000000..b9588c7
--- /dev/null
+++ b/2020/18/solution2.py
@@ -0,0 +1,112 @@
+import re
+
+example1 = '1 + 2 * 3 + 4 * 5 + 6'
+example2 = '1 + (2 * 3) + (4 * (5 + 6))'
+example3 = '2 * 3 + (4 * 5)'
+example4 = '5 + (8 * 3 + 9 + 3 * 4 * 3)'
+example5 = '5 * 9 * (7 * 3 * 3 + 9 * 3 + (8 + 6 * 4))'
+example6 = '((2 + 4 * 9) * (6 + 9 * 8 + 6) + 6) + 2 + 4 * 2'
+
+with open('input') as f:
+    expressions = f.readlines()
+
+
+def calc(op, a, b):
+    if op == '+':
+        return a + b
+    elif op == '*':
+        return a * b
+    else:
+        raise Exception(f'Operator "{op}" not known')
+
+
+class Node:
+    leaf_value = None
+
+    def __init__(self, expression):
+        # print('Processing', expression)
+        while expression[0] == '(':
+            level = 0
+            split = None
+            closing_bracket = None
+            for idx, char in enumerate(expression):
+                if char == '(':
+                    level += 1
+                elif char == ')':
+                    level -= 1
+                    if level == 0 and closing_bracket is None:
+                        closing_bracket = idx
+
+                if level == 0 and char == '*' and split is None:
+                    split = idx
+            # print(f'Found split at {i} within {expression}')
+            if closing_bracket + 1 == len(expression):
+                # print('stipping unneeded parens')
+                expression = expression[1:-1]
+            else:
+                if split is not None:
+                    # self.split_at(expression, split)
+                    self.split_at(expression, split)
+                else:
+                    self.split_at(expression, closing_bracket + 2)
+                return
+        if '(' in expression:
+            level = 0
+            split = None
+            for idx, char in enumerate(expression):
+                if char == '(':
+                    level += 1
+                elif char == ')':
+                    level -= 1
+
+                if level == 0 and char == '*' and split is None:
+                    split = idx
+            if split is not None:
+                self.split_at(expression, split)
+            else:
+                self.split_at(expression, expression.find('+'))
+        elif '*' in expression:
+            self.split_at(expression, expression.find('*'))
+        elif '+' in expression:
+            self.split_at(expression, expression.find('+'))
+        else:
+            self.leaf_value = int(expression.strip())
+
+    def split_at(self, expression, idx):
+        left = expression[:idx].strip()
+        right = expression[idx + 1:].strip()
+        op = expression[idx]
+        # print(f'Splitting "{left}" "{op}" "{right}"')
+        self.left = Node(left)
+        self.right = Node(right)
+        self.op = op
+
+    @ property
+    def value(self):
+        if self.leaf_value is not None:
+            return self.leaf_value
+        return calc(self.op, self.left.value, self.right.value)
+
+
+def solve(line):
+    return Node(line.strip()).value
+
+
+print(example1, '=', solve(example1))
+print(example2, '=', solve(example2))
+print(example3, '=', solve(example3))
+print(example4, '=', solve(example4))
+print(example5, '=', solve(example5))
+print(example6, '=', solve(example6))
+
+# should be 16530240
+example7 = '3 + (8 * 2 * 4) * 8 * (2 + (8 * 5 + 3 * 4 + 4)) * (2 * (5 * 6))'
+print(example7, '=', solve(example7), 'should be', '16530240')
+
+
+print('Solution')
+# for expr in expressions:
+#     print(expr.strip(), '=', solve(expr))
+
+print(sum(map(solve, expressions)))
+