diff --git a/src/main.rs b/src/main.rs
index cd921fc..3fd2de1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,5 @@
 mod tasks;
 
 fn main() {
-    tasks::day03::run();
+    tasks::day04::run();
 }
diff --git a/src/tasks/day04.rs b/src/tasks/day04.rs
new file mode 100644
index 0000000..0099807
--- /dev/null
+++ b/src/tasks/day04.rs
@@ -0,0 +1,17 @@
+use std::ops::RangeInclusive;
+
+pub fn run() {
+    let range = 109165..=576723;
+    task1(&range);
+}
+
+fn task1(range: &RangeInclusive<i32>) {
+    let count = range
+        .clone()
+        .map(|v| format!("{}", v))
+        .filter(|s| s.chars().zip(s.chars().skip(1)).any(|(a, b)| a == b))
+        .filter(|s| s.chars().zip(s.chars().skip(1)).all(|(a, b)| a <= b))
+        .count();
+
+    println!("Task 1: There are {} valid passwords in the range", count);
+}
diff --git a/src/tasks/mod.rs b/src/tasks/mod.rs
index 385f909..c78254c 100644
--- a/src/tasks/mod.rs
+++ b/src/tasks/mod.rs
@@ -1,2 +1,3 @@
 pub mod day01;
 pub mod day03;
+pub mod day04;