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

int main() {
  int A, B, C, D; cin >> A >> B >> C >> D;
  int ans = 0;
  while(true){
    if(A == 0 or B < C) break;
    if(C+1 <= D){
      ans++;
      A--;
      B -= C;
      D -= C+1;
    }else{
      break;
    }
  }
  cout << ans << endl;
}