#include <iostream>

using namespace std;

int main(){
    int a,b,c,d;
    cin>>a>>b>>c>>d;
    
    int aa,bb;
    if(a*c<=b){
        aa=a;
    }
    else{
        aa=b/c;
    }
    bb=aa*c;
    while(aa+bb>d){
        aa--;
        bb=aa*c;
    }
    
    cout<<aa<<'\n';
    
    return 0;
}