#include <cstdio>
#include <climits>
#include <vector>
#include <algorithm>
#include <queue>
#include <stdio.h>
#include <string.h>


#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define INF 99999999

using namespace std;

int main() {
    int a,b,x,y;
    scanf("%d %d %d %d",&a,&b,&x,&y);
    double ans = (a + b) * min( (y / (double)b) , (x / (double)a));
    
    printf("%.20f\n",ans);
    
    
    
    
    
    
    
    
}