diff --git a/data/examples/21.txt b/data/examples/21.txt
new file mode 100644
index 0000000..e69de29
diff --git a/src/bin/21.rs b/src/bin/21.rs
new file mode 100644
index 0000000..791a4f8
--- /dev/null
+++ b/src/bin/21.rs
@@ -0,0 +1,26 @@
+advent_of_code::solution!(21);
+
+pub fn part_one(input: &str) -> Option<u64> {
+    None
+}
+
+pub fn part_two(input: &str) -> Option<u64> {
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, None);
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, None);
+    }
+}