#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 100;

int a, b, n;
int f[N];

int main()
{
    f[1] = 1, f[2] = 1;
    while (cin >> a >> b >> n && (a + b + n))
    {
        int i;
        for (i = 3; i < 100; i ++ )
        {
            f[i] = (a * f[i - 1] + b * f[i - 2]) % 7;
            if (f[i] == 1 && f[i - 1] == 1)
                break; // //当找到两个连续1时走完一个周期周期为i-2
        }
        f[0] = f[i - 2];
        n = n % (i - 2);
        cout << f[n] << endl;
    }
    return 0;
}