杭电 1001

#include<stdio.h>

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

注意： 题中要求的是follow by a blank line 所以在输出的时候需要输出两次\n\n