Problem-1001：Sum Problem

Sum Problem

Sample code ：

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