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

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll n, x, a, b;
    cin >> n >> x >> a >> b;

    // 普通にたたく
    ll attack_num;
    if(x%a==0){
        attack_num = x/a;
    }else{
        attack_num = x/a + 1;
    }

    // 回復
    ll overflow = pow(2, n-1);
    ll rest = overflow - x;
    ll heal_num;
    if(rest%b==0){
        heal_num = rest/b;
    }else{
        heal_num = rest/b + 1;
    }

    ll ans = min(attack_num, heal_num);
    p(ans);
    return 0;
}