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>
int main(){
  char c[10];
  char in;
  int i=0;
  while(1){
    scanf("%c",&in);
    if(in=='\n')break;

    if(in == '0') {
      c[i]=in;
      i++;
    }
 if(in == '1') {
      c[i]=in;
      i++;
    }
 if(in == 'B') {
      c[i]='\0';
      if(i>0)i--;
    }
  }
  printf("%s\n",c);
  return 0;
}