#include <iostream>
#include <iomanip>

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