func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(NULL);     cout.tie(NULL);     int t;     cin >> t;     while (t--) {       long long a, b, k;       cin >> a >> b >> k;       if (k % 2 == 0)         cout << a * (k / 2) - b * (k / 2) <<   n ;       else         cout << a * (k / 2 + 1) - b * (k / 2) <<   n ;     }     return 0;   }   