View Code of Problem 30

# include<stdio.h>
int main(void)
{
  int n,i,sum;
  while(scanf("%d",&n)!=EOF)
  {
    sum = 0;
    for(i=1;i<=n;++i)
    {
      sum = sum + i;
    }
    printf("%d\n",sum);
  }
  return 0;
}