大侠们说说算法咯

各位大侠帮忙看看下面哪错了
#include <stdio.h>
int main()
{
    long n,i,k,r,r0;
    int f[200],A,B;
    f[1]=1;f[2]=1;
    while(scanf("%d%d%ld",&A,&B,&n)!=EOF)
    {
        if(A==0&&B==0&&n==0)
            break;
        if(n==1||n==2)
            r=f[n]%7;
        else
        {
           k=0;
           i=3;
           f[i]=(A%7*f[i-1]+B%7*f[i-2])%7;
           r0=f[i];
           r=r0;
           for(i=4;i<=n;i++)
           {
               f[i]=(A%7*f[i-1]+B%7*f[i-2])%7;
               r=f[i];
               k++;
           if(r==r0&&i!=n)
               {
        n=n-k+1;
                i=i-k+1;
               }
               k=0;
               if(i==n)
               break;
           }
       }

            printf("%ld\n",r);
    }
    return 0;
}