#include <iostream>
#include <algorithm>
#include <math.h>
using namespace std;

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

  int max_h = pow(2, n - 1);
  int y = max_h - x;
  
  x = (x / a) + ((x % a) != 0);
  y = (y / b) + ((y % b) != 0);

  cout << min(x, y) << endl;

  return 0;
}