diff --git a/2019/aoc2019/day21.py b/2019/aoc2019/day21.py
new file mode 100644
index 0000000..d96c197
--- /dev/null
+++ b/2019/aoc2019/day21.py
@@ -0,0 +1,44 @@
+from typing import TextIO
+
+from aoc2019.intcode import read_program, Computer
+
+
+def send_input(computer: Computer, program: str) -> None:
+    for c in program:
+        computer.send_input(ord(c))
+
+
+def run(data: TextIO, program: str) -> int:
+    computer = Computer(read_program(data))
+
+    send_input(computer, program)
+    computer.run()
+
+    return computer.output.pop()
+
+
+def part1(data: TextIO) -> int:
+    program = """\
+    OR A J
+    AND B J
+    AND C J
+    NOT J J
+    AND D J
+    WALK
+    """
+
+    return run(data, program)
+
+
+def part2(data: TextIO) -> int:
+    program = """\
+    NOT H J
+    OR C J
+    AND A J
+    AND B J
+    NOT J J
+    AND D J
+    RUN
+    """
+
+    return run(data, program)