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

int main() {
  int A,B,C,D;
  cin >> A>>B>>C>>D;
  if(D/(C+1)<B/C){
     if(D/(C+1)>=A){
     cout<<A<<endl;
     }
    else  if(D/(C+1)<A){
    cout<<D/(C+1)<<endl;
    }
   else{
   cout<<0<<endl;
   }
}
else if(D/(C+1)>B/C){
    if(B/C<A){
    cout<<B/C<<endl;
    }
   else if(B/C>=A){
   cout<<A<<endl;
   }
   else{
   cout<<0<<endl;
   }

}
else{
cout<<0<<endl;
}
}