#include <iostream>
#include <math.h>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#define REP(i,n) for(int i=0;i<n;i++)
typedef long long ll;

using namespace std;
int kaijo(int n){
	int ans = 1;
	if (n != 0){
		for (int i = 0; i < n; i++){
			ans *= (n - i);
		}
	}
	else{
		ans = 1;
	}
	return ans;
}

int main(){
	int n;
	ll x, a, b, ax, bx;
	ll mx;
	int cnt1 = 0;
	int cnt2 = 0;
	cin >> n >> x >> a >> b;
	mx = pow(2, n - 1);
	ax = x; bx = x;
	while (1){
		ax -= a;
		cnt1++;
		if (ax <= 0){
			break;
		}
	}
	while (1){
		bx += b;
		cnt2++;
		if (bx >= mx){
			break;
		}
	}
	if (cnt1 < cnt2){
		cout << cnt1 << endl;
	}
	else{
		cout << cnt2 << endl;
	}
	return 0;
}