diff --git a/2019/1/day1.kt b/2019/1/day1.kt
new file mode 100644
index 0000000..bfda102
--- /dev/null
+++ b/2019/1/day1.kt
@@ -0,0 +1,23 @@
+package moe.kageru.aoc
+
+fun main() {
+    val input = generateSequence(::readLine)
+        .map { it.toLong() }
+        .toList();
+    println("Part 1: ${part1(input)}")
+    println("Part 2: ${part2(input)}")
+}
+
+fun part1(numbers: List<Long>): Long = numbers.map(::cost).sum()
+
+fun part2(numbers: List<Long>): Long = numbers.map { costRec(it, 0) }.sum()
+
+fun cost(mass: Long): Long = (mass / 3) - 2
+
+tailrec fun costRec(mass: Long, acc: Long): Long {
+    val cost = cost(mass)
+    return when {
+        cost <= 0 -> acc
+        else -> costRec(cost, acc + cost)
+    }
+}