View Code of Problem 30

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