diff --git a/zeta_python/completed/17266.py b/zeta_python/completed/17266.py
new file mode 100644
index 0000000..9e2a073
--- /dev/null
+++ b/zeta_python/completed/17266.py
@@ -0,0 +1,8 @@
+if __name__ == "__main__":
+    N, M = int(input()), int(input())
+    X = list(map(int, input().split()))
+
+    max_dx = max([X[i + 1] - X[i] for i in range(M - 1)], default=0)
+    max_h = max_dx // 2 if max_dx % 2 == 0 else max_dx // 2 + 1
+
+    print(max([max_h, N - X[-1], X[0]]))