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

int main() {
  int A,B,C,D;
  cin >> A>>B>>C>>D;
if(A+A*C>=D){
  if(A*C<=B){
  cout<<A<<endl;
  }
  else if(A*C>B){
  cout<<B/C<<endl;
  }
}
else if(A+A*C<D){
  if(A*C<=B){
    for (int a = 0; A+A*C < D; a++) {
    A--;
    }
  cout<<A<<endl;
  }
  else if(A*C>B){
    if(B/C+B/C*C>D){
    for (int b = 0; B/C+B/C*C < D; b++) {
    B--;
    }
  cout<<B/C<<endl;
  }
  }
    if(B/C+B/C*C<=D){
  cout<<B/C<<endl;
  }
}
}