Number Sequence

#include<cstdio>
int main()
{
    int n;
    int A,B;
    int a[10000]= {0,1,1};
    while(scanf("%d%d%d",&A,&B,&n)&&(A||B||n))
    {
        int i;
        for(i=3; i<10000; i++)
        {
            a[i]=(A*a[i-1]+B*a[i-2])%7;
            if(a[i-1]==1&&a[i]==1) break;
        }
        n=n%(i-2);
        if(n==0) n=i-2;
        printf("%d\n",a[n]);
    }
    return 0;
}