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 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<string.h>
 
int main(){
  char s[11];
  scanf("%s",s);
 
  int j=0;
  char array[11]={'\0'};
  int len=strlen(s);
  for(int i=0;i<len;i++){
    if(s[j]=='0'){
      array[i]='0';
    }else if(s[j]=='1'){
      array[i]='1';
    }else if(s[j]=='B'){
      array[i-1]='\0';
      i--;
    }
    j++;
    if(j==len){
      break;
    }
  }
  printf("%s",array);
  return 0;
}