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