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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <stdio.h>

int sum(int n);

int sum(int n)
{
        int result = 0;

        do
        {
                result += n;
        } while(n-- > 0);

        return result;
}

int main(void)
{
        int n;

        printf("请输入n的值：");
        scanf("%d", &n);

        printf("1+2+3+...+(n-1)+n的结果是：%d\n", sum(n));

        return 0;
    }