python/TangDou/LanQiaoBei/LanQiaoBeiWhitePaper/10_ZhengZhengShuSum.cpp

#include <bits/stdc++.h>

using namespace std;
int n;
int sum;

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++)
        sum += i;
    printf("%d", sum);
    return 0;
}