#include<bits/stdc++.h>
using namespace std;

int main(){
    int a,b,x,y;
    cin>>a>>b>>x>>y;
    int sum = 0;
    int max1 = max(x,y);
    int onlyf = ceil((double)a / x) + ceil((double)b / x);
    int h = ceil(max(a,b)/(double)(y));
    sum = onlyf;
    for(int i = 0;i<=h;i++){
        int sya = a - y*i;
        int syb = b - y*i;
        if(sya<0){
            sya = 0;
        }
        if(syb<0){
            syb = 0;
        }
        int m = ceil((double)sya/x);
        int n = ceil((double)syb/x);
        int quanbu = m+n+i;
        sum = min(quanbu,sum);
    }
    cout<<sum;
    return 0;
}