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 10.0.0) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<string.h>
int main(){
	char key[15];
	scanf("%s", key);
//	char temp[15];
	int len=strlen(key);
	for(int i=0; i<len; i++){
		int ctrb=0;
		int j=i;
		while(key[j]=='B'){
			ctrb++;
			j++;
		}
		while(ctrb){
			key[i-ctrb]=' ';
			ctrb--;
		}
	}
	for(int i=0; i<len; i++){
		if(key[i]=='1' || key[i]=='0'){
			printf("%c", key[i]);
		}
	}
	
	return 0;
}