hdu-2114-Calculate S(n)

#include<stdio.h>
int main()
{
int n;
while(scanf("%d",&n)!=EOF)
{
_int64 sum;
n%=10000;
sum=(n*(n+1)/2)%10000;
sum=sum*sum%10000;
if(sum<10)
printf("000%I64d\n",sum);
else if(sum<100)
printf("00%I64d\n",sum);
else if(sum<1000)
printf("0%I64d\n",sum);
else
printf("%I64d\n",sum);
}
return 0;
}