func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, m, k, ans(0);     bool flg = true;     cin >> n >> m >> k;     int ar[n * m];     for (int a = 0; a < n * m; a++) cin >> ar[a];     sort(ar, ar + n * m);     int median = (n * m % 2) ? ar[n * m / 2] : ar[(n * m + 1) / 2];     for (int a = 0; a < n * m; a++) {       if (abs(median - ar[a]) % k != 0) flg = false;       ans += abs(median - ar[a]) / k;     }     if (flg)       cout << ans;     else       cout << -1;   }   