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

#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define repi(i,a,b) for(int i=int(a);i<(int)(b);i++)
#define all(x) (x).begin(),(x).end()
#define foreach(u,v) for(auto (u) : (v))
#define pb push_back
#define mp make_pair
#define mt make_tuple

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<ll, ll> pll;
typedef vector<ll> vl;

const int inf = 1e9;
const ll linf = 1e18;
const ll mod = 1e9 + 7;
const double eps = 1e-9;

int main()
{
  ll n, x, a, b;
  cin >> n >> x >> a >> b;

  ll k = 1LL<<(n-1);
  ll t1 = (k-x+b-1)/b;
  ll t2 = (x+a-1)/a;

  cout << min(t1, t2) << endl;

  return 0;
}