From 7e6f998ec6c4a62ca438b86f3236ab9e80c21a11 Mon Sep 17 00:00:00 2001
From: Ren Baoshuo <i@baoshuo.ren>
Date: Sun, 27 Dec 2020 20:34:21 +0800
Subject: [PATCH] =?UTF-8?q?P7157=20=E3=80=8CdWoi=20R1=E3=80=8DPhysics=20Pr?=
 =?UTF-8?q?oblem?=
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R44326556
---
 problem/P7157/P7157.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)
 create mode 100644 problem/P7157/P7157.cpp

diff --git a/problem/P7157/P7157.cpp b/problem/P7157/P7157.cpp
new file mode 100644
index 00000000..0d1b2bbf
--- /dev/null
+++ b/problem/P7157/P7157.cpp
@@ -0,0 +1,10 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int main() {
+    long long n, k;
+    cin >> n >> k;
+    cout << n * (n - 1) / 2 - k << endl;
+    return 0;
+}