#include<iostream>
#include<string>
using namespace std;
int a[21];
int A=1, B=1, n;
int f(int x)
{
    if (x == 1 || x == 2)return 1;
    if (a[x])return a[x];
    else return a[x] = (A*f(x - 1) + B*f(x - 2)) % 7;
}
int main()
{
    while (1){
        cin >> A >> B >> n;
        if (A == 0 && B == 0 && n == 0)break;
        memset(a, 0, sizeof(a));
        f(20);
        a[0] = a[16];
        a[1] = a[17];
        a[2] = a[18];
        if (n == 1 || n == 2){
            cout << "1\n";
        }
        else{
            cout << a[n % 16] << endl;
        }
    }

    system("pause");
    return 0;
}