#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;
int main() {
    int a,b,x,y;cin>>a>>b>>x>>y;
    float ans = fmin(x*b,a*y)/b+fmin(y*a,b*x)/a;
    cout << setprecision(9) << ans<< endl;
    return 0;
}