算法路-HDU-ACM---1001

#include <stdio.h>

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