#include <iostream>
using namespace std;

int main(){
    int A,B,C,D;
    int veg=0,meat=0,i,j;
    int total=0;

    cin>>A>>B>>C>>D;

    while(total<=D && veg<=A && meat<=B){
        total=veg+meat;
        veg++;
        meat=veg*C;
    }

    cout<<veg-1<<endl;
    return 0;
}