#include <bits/stdc++.h>   using namespace std;   int main() {     long long x, y;     cin >> x >> y;     long long n;     cin >> n;     n %= 6;     if (n == 0) n = 6;     long long data[7];     data[1] = x;     data[2] = y;     for (int i = 3; i <= 6; i++) {       data[i] = data[i - 1] - data[i - 2];     }     for (int i = 1; i <= 6; i++)       if (data[i] < 0) data[i] += 1000000007;     if (data[n] < 0) data[n] += 1000000007;     cout << data[n] % 1000000007 <<   n ;     return 0;   }   