func_code_string: #include <bits/stdc++.h>   using namespace std;   long long n, m, k, ans = 0;   int main() {     cin >> n >> m >> k;     if (n - 1 + m - 1 < k) {       cout << -1 << endl;       return 0;     }     long long buf = sqrt(n);     buf++;     for (int i = 0; i <= buf; i++) {       long long x = n / (i + 1);       if (k - i < 0) continue;       long long y = m / (k - i + 1);       ans = max(ans, x * y);     }     for (int i = 1; i <= buf; i++) {       long long cut = n / i - 1;       if (cut < 0) continue;       long long left = k - cut;       if (left < 0) left = 0;       ans = max(ans, i * (m / (left + 1)));     }     cout << ans << endl;     return 0;   }   