diff --git a/.gitignore b/.gitignore
index 7c6571e..a2246dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 venv
 *.pyc
+target/
diff --git a/2021/01/example b/2021/01/example
new file mode 100644
index 0000000..167e291
--- /dev/null
+++ b/2021/01/example
@@ -0,0 +1,10 @@
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diff --git a/2021/01/input b/2021/01/input
new file mode 100644
index 0000000..fd426dc
--- /dev/null
+++ b/2021/01/input
@@ -0,0 +1,2000 @@
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diff --git a/2021/01/part1.rs b/2021/01/part1.rs
new file mode 100644
index 0000000..eaacea1
--- /dev/null
+++ b/2021/01/part1.rs
@@ -0,0 +1,25 @@
+use std::io::stdin;
+use std::io::BufRead;
+
+fn main() {
+    let mut prev: Option<i32> = None;
+    let mut increased = 0;
+    for line in stdin().lock().lines() {
+        let cur = line.unwrap().parse::<i32>().unwrap();
+
+        match prev {
+            None => println!("{} (N/A)", cur),
+            Some(prev) => {
+                if cur > prev {
+                    increased += 1;
+                }
+                let evaluate = if cur > prev { "increased" } else { "decreased" };
+                println!("{} ({})", cur, evaluate)
+            }
+        }
+
+        prev = Some(cur);
+    }
+
+    println!("{}", increased)
+}
diff --git a/2021/01/part2.rs b/2021/01/part2.rs
new file mode 100644
index 0000000..47440ee
--- /dev/null
+++ b/2021/01/part2.rs
@@ -0,0 +1,27 @@
+use itertools::Itertools;
+use std::io::stdin;
+use std::io::BufRead;
+
+fn main() {
+    let mut prev: Option<i32> = None;
+    let mut increased = 0;
+    for (a, b, c) in stdin()
+        .lock()
+        .lines()
+        .map(|line| line.unwrap().parse::<i32>().unwrap())
+        .tuple_windows()
+    {
+        let sum = a + b + c;
+        match prev {
+            Some(prev) => {
+                if sum > prev {
+                    increased += 1
+                }
+            }
+            _ => (),
+        }
+        prev = Some(sum)
+    }
+
+    println!("{}", increased)
+}
diff --git a/2021/Cargo.lock b/2021/Cargo.lock
new file mode 100644
index 0000000..9d91f08
--- /dev/null
+++ b/2021/Cargo.lock
@@ -0,0 +1,25 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aoc-2021"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+]
+
+[[package]]
+name = "either"
+version = "1.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
+
+[[package]]
+name = "itertools"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "69ddb889f9d0d08a67338271fa9b62996bc788c7796a5c18cf057420aaed5eaf"
+dependencies = [
+ "either",
+]
diff --git a/2021/Cargo.toml b/2021/Cargo.toml
new file mode 100644
index 0000000..315770b
--- /dev/null
+++ b/2021/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "aoc-2021"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+itertools = "0.10.1"
+
+[lib]
+name = "util"
+path = "util/main.rs"
+
+[[bin]]
+name = "day-01-part-1"
+path = "01/part1.rs"
+
+[[bin]]
+name = "day-01-part-2"
+path = "01/part2.rs"
diff --git a/2021/util/main.rs b/2021/util/main.rs
new file mode 100644
index 0000000..c495ae7
--- /dev/null
+++ b/2021/util/main.rs
@@ -0,0 +1,11 @@
+use std::fs::File;
+use std::io::BufRead;
+use std::io::BufReader;
+use std::io::Lines;
+
+pub mod math;
+
+pub fn file_lines(path: String) -> Lines<BufReader<File>> {
+    let input = File::open(path).unwrap();
+    return BufReader::new(input).lines();
+}
diff --git a/2021/util/math.rs b/2021/util/math.rs
new file mode 100644
index 0000000..33624d4
--- /dev/null
+++ b/2021/util/math.rs
@@ -0,0 +1,7 @@
+pub fn sum(x: i32, y: i32) -> i32 {
+    x + y
+}
+
+pub fn sub(x: i32, y: i32) -> i32 {
+    x - y
+}