[C++]백준 8393번:합

https://www.acmicpc.net/problem/8393

#include <iostream>

#include <string>

using namespace std;

int main() {

int N;

while (true) {

cin >> N;

if (N >= 1 && N <= 10000)

break;

}

int sum = 0;

for (int i = 1; i <= N; i++)

sum += i;

cout << sum;

}