HDON_1021_Fibonacci Again

AC代码：

#include <iostream>
#include <cstdio>
using namespace std;
int main(void)
{
    freopen("in.txt","r",stdin);
    long long n;
    while(scanf("%lld",&n)!=EOF)
    {
        n++;
        long long s,s1=7,s2=11;
        if(n==1)
        {
            s=s1;
        }
        if(n==2)
        {
            s=s2;
        }
        else 
        {
            for(long long i=3;i<=n;i++)
            {
                s=(s1+s2)%3;
                s1=s2;
                s2=s;
            }
        }
        
        if(s%3==0)
            printf("yes\n");
        else
            printf("no\n");
        
    }

    fclose(stdin);
    return 0;
}