容器vector

#include<iostream>
#include<vector>
using namespace std;
vector <int> v;
int main() {
	int n;
    cin >> n;
    for(int i=1; i<=n; i++) {
        v.push_back(i);
    }
    int sum = 0;
    for(int i=0; i<v.size(); i++) {
		sum += v[i];
    }
    cout << sum;
}