diff --git a/2021/day7.py b/2021/day7.py
new file mode 100644
index 0000000..e2271ca
--- /dev/null
+++ b/2021/day7.py
@@ -0,0 +1,32 @@
+import sys
+
+
+def main():
+    lines = [line.rstrip() for line in sys.stdin]
+    positions = list(map(int, lines[0].split(",")))
+    solve(positions, lambda x, y: abs(x - y))
+    solve(positions, lambda x, y: sum(range(abs(x - y) + 1)))
+
+
+def solve(positions, acc_f):
+    a, b = min(positions), max(positions)
+    while True:
+        mid = (a + b) // 2
+        conso = consume(positions, mid, acc_f)
+        conso_up = consume(positions, mid + 1, acc_f)
+        conso_down = consume(positions, mid - 1, acc_f)
+        if conso < conso_up and conso < conso_down:
+            break
+        if conso_up < conso:
+            a = mid
+        else:
+            b = mid
+    print(conso)
+
+
+def consume(positions, toward, acc_f):
+    return sum(acc_f(pos, toward) for pos in positions)
+
+
+if __name__ == "__main__":
+    main()