#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define fbo find_by_order
#define ook order_of_key
 
typedef long long ll;
typedef pair<ll,ll> ii;
typedef vector<int> vi;
typedef long double ld; 
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> pbds;
typedef set<ll>::iterator sit;
typedef map<ll,ll>::iterator mit;

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);
	ll n,x,a,b; cin>>n>>x>>a>>b;
	ll m1 = (x+a-1)/a;
	ll m2 = ((1LL<<(n-1))-x+b-1)/b;
	cout<<min(m1,m2)<<'\n';
}