#include <bits/stdc++.h>   using namespace std;   int main() {     long long a, b, k = 0;     long long x, y, z = 0;     long long hsl[1002];     cin >> a;     for (int i = 1; i <= a; i++) {       y = 0;       z = 0;       cin >> b >> k >> x;       if (x % 2 == 0) {         y = x / 2;         z = x / 2;       } else {         z = x / 2 + 1;         y = x / 2;       }       z = z * b;       y = y * k;       z = z - y;       hsl[i] = z;     }     for (int i = 1; i <= a; i++) {       cout << hsl[i] << endl;     }   }   