Problem:
Score : 100 points

Problem Statement

There are N children in AtCoder Kindergarten. Mr. Evi will arrange the children in a line, then give 1 candy to the first child in the line, 2 candies to the second child, ..., N candies to the N-th child. How many candies will be necessary in total?

Constraints

1≦N≦100

Input

The input is given from Standard Input in the following format:

N

Output

Print the necessary number of candies in total.

Sample Input 1

3

Sample Output 1

6

The answer is 1+2+3=6.

Sample Input 2

10

Sample Output 2

55

The sum of the integers from 1 to 10 is 55.

Sample Input 3

1

Sample Output 3

1

Only one child. The answer is 1 in this case.

Solution in C++14 (Clang 3.8.0) (judge verdict: Accepted)

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define ll long long
#define Di 3.1415926
#include<math.h>
#define INF 0x3f3f3f3f
using namespace std;
ll  gcd(ll a,ll b)
{
    return a%b? gcd(b,a%b):b;
}

int main()
{


   int n,sum=0;
   cin>>n;
   for(int i=1;i<=n;i++)
   {
       sum+=i;

   }

    cout<<sum<<endl;



 return 0;
}