diff --git a/src/holt59/aoc/2015/day21.py b/src/holt59/aoc/2015/day21.py
new file mode 100644
index 0000000..cf71059
--- /dev/null
+++ b/src/holt59/aoc/2015/day21.py
@@ -0,0 +1,66 @@
+import itertools
+import sys
+from math import ceil
+from typing import TypeAlias
+
+Modifier: TypeAlias = tuple[str, int, int, int]
+
+WEAPONS: list[Modifier] = [
+    ("Dagger", 8, 4, 0),
+    ("Shortsword", 10, 5, 0),
+    ("Warhammer", 25, 6, 0),
+    ("Longsword", 40, 7, 0),
+    ("Greataxe", 74, 8, 0),
+]
+
+ARMORS: list[Modifier] = [
+    ("", 0, 0, 0),
+    ("Leather", 13, 0, 1),
+    ("Chainmail", 31, 0, 2),
+    ("Splintmail", 53, 0, 3),
+    ("Bandedmail", 75, 0, 4),
+    ("Platemail", 102, 0, 5),
+]
+
+RINGS: list[Modifier] = [
+    ("", 0, 0, 0),
+    ("Damage +1", 25, 1, 0),
+    ("Damage +2", 50, 2, 0),
+    ("Damage +3", 100, 3, 0),
+    ("Defense +1", 20, 0, 1),
+    ("Defense +2", 40, 0, 2),
+    ("Defense +3", 80, 0, 3),
+]
+
+
+lines = sys.stdin.read().splitlines()
+
+player_hp = 100
+
+boss_attack = int(lines[1].split(":")[1].strip())
+boss_armor = int(lines[2].split(":")[1].strip())
+boss_hp = int(lines[0].split(":")[1].strip())
+
+
+min_cost, max_cost = 1_000_000, 0
+for equipments in itertools.product(WEAPONS, ARMORS, RINGS, RINGS):
+    if equipments[-1][0] != "" and equipments[-2] == equipments[-1]:
+        continue
+
+    cost, player_attack, player_armor = (
+        sum(equipment[1:][k] for equipment in equipments) for k in range(3)
+    )
+
+    if ceil(boss_hp / max(1, player_attack - boss_armor)) <= ceil(
+        player_hp / max(1, boss_attack - player_armor)
+    ):
+        min_cost = min(cost, min_cost)
+    else:
+        max_cost = max(cost, max_cost)
+
+
+answer_1 = min_cost
+print(f"answer 1 is {answer_1}")
+
+answer_2 = max_cost
+print(f"answer 2 is {answer_2}")
diff --git a/src/holt59/aoc/inputs/holt59/2015/day21.txt b/src/holt59/aoc/inputs/holt59/2015/day21.txt
new file mode 100644
index 0000000..db43742
--- /dev/null
+++ b/src/holt59/aoc/inputs/holt59/2015/day21.txt
@@ -0,0 +1,3 @@
+Hit Points: 100
+Damage: 8
+Armor: 2