#include <bits/stdc++.h>
#define PB push_back
#define MP make_pair
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(a) (a).begin(),(a).end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
const int INF=1e9;
const int MOD=100000;
int B=1000000;
int main(){
      int a,b,x,y;
      cin>>a>>b>>x>>y;
      double xx=(double)x/(double)a;
      double yy=(double)y/(double)b;
      printf("%.10f\n",min(xx,yy)*((double)a+(double)b));
}