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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include <stdlib.h>




int main() {
	char s[11];
	char r[11];
	char buf[64];
	int i,n,j,dummy,k;
	scanf("%s", s, 11);
	for (n = 0; s[n] != '\0'; n++);

	for (i = 0, j=0; s[i] != '\0'; i++) {
		fgets(buf, 64, stdin);
		if (s[i] == 'B') {
			//j--;
			continue;
		}
		r[j] = s[i];
		j++;
		for (k = 0, r[j] = '\0'; k < j; k++) printf("%c", r[k]);
	}
	return 0;
}