code1

/*
    HDU 1005 number sequence
*/

#include<stdio.h>
#define SEQ_LEN 100000

int main(void)
{
    long n;
    int a,b,len,seq[SEQ_LEN];

    while(scanf("%d%d%ld",&a,&b,&n),a||b||n)
    {
        len=3;
        seq[1]=seq[2]=1;
        seq[3]=(a*seq[2]+b*seq[1])%7;
        while((seq[len]!=1||seq[len-1]!=1)&&len<SEQ_LEN-1)
            len++,seq[len]=(a*seq[len-1]+b*seq[len-2])%7;
        seq[0]=seq[len-2];
        printf("%d\n",seq[n%(len-2)]);
    }

    return 0;
}