#include <bits/stdc++.h>

#define REP(i, x, n) for(int i = x; i < (int)(n); i++)
#define rep(i, n) REP(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define F first
#define S second
#define mp make_pair

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;

int main() {
	double EPS = 1e-6;
	int a, b, x, y;
	cin >> a >> b >> x >> y;
	double lb = 0;
	double ub = max(x, y);
	double ans = 0;
	rep(i, 100) {
		double v = (lb + ub) / 2;
		if(a * v <= x && b * v <= y) {
			lb = v;
			ans = max(ans, a * v + b * v);
		}
		else {
			ub = v;
		}
	}
	printf("%.10f\n", ans);
  return 0;
}