func_code_string: #include <bits/stdc++.h>   using namespace std;   long long n, k, m, d, i = 0, b = 1, ans = 0;   int main(void) {     cin >> n >> k >> m >> d;     for (i = 1; i <= d && b <= n; i++, b += k) {       ans = max(ans, min(m, n / b) * i);     }     cout << ans;     return 0;   }   