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)))