/* -*- coding: utf-8 -*-
 *
 * 598.cc: No.598 オーバーフローファンタジー - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

typedef long long ll;
typedef vector<int> vi;
typedef queue<int> qi;
typedef pair<int,int> pii;

/* global variables */

/* subroutines */

/* main */

int main() {
  int n;
  ll x, a, b;
  scanf("%d%lld%lld%lld", &n, &x, &a, &b);

  int k0 = (x + a - 1) / a;
  int k1 = ((1LL << (n - 1)) - x + b - 1) / b;
  printf("%d\n", min(k0, k1));
  return 0;
}