func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long mod = 1e9 + 7;   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     ;     long long x, y;     cin >> x >> y;     long long n;     cin >> n;     long long ans;     switch (n % 6) {       case 1:         ans = x;         break;       case 2:         ans = y;         break;       case 3:         ans = y - x;         break;       case 4:         ans = -x;         break;       case 5:         ans = -y;         break;       case 0:         ans = x - y;         break;     }     cout << (ans + 2 * mod) % mod;   }   