入门训练 Fibonacci数列

http://lx.lanqiao.cn/problem.page?gpid=T4

#include <stdio.h>
int main()
{
    unsigned long s=0,f1=1,f2=1,f3=1,n=0;
    scanf("%d",&n);
     
    if(n>2)
    for(s=3;s<=n;s++)
    {
         f3=(f2+f1)%10007;
         f1=f2;
         f2=f3;
    }
 
     printf("%d",f3);
     return 0;
 }