#include <bits/stdc++.h>

using namespace std;
double a, b, x, y;
void input() { cin >> a >> b >> x >> y; }
void solve() { cout << (double)(a + b) * (min(x / a, y / b)) << endl; }

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(12);
  input();
  solve();
}