题解

#include<bits/stdc++.h>
#define ll long long                                                        //防伪标识
#define MAXN 1005
#define maxn 10005
#define MAXM 10000
#define maxm 1000005
using namespace std;
int h,sum;
int main(){
	cin>>h;
	for(int i = 1;i<=h;i++)
		sum+=i;
	cout<<sum;
	return 0;
}