#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

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

    long long y = (1 << (n - 1)) - x;
    long long ans = min<long long>((x - 1 + a) / a, (y - 1 + b) / b);
    cout << ans << endl;

    return 0;
}