View Code of Problem 30

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