import std.stdio;
import std.algorithm;
import std.string;
import std.conv;
import std.math;

void main() {
  int n = readln.chomp.to!int;
  int x = readln.chomp.to!int;
  int a = readln.chomp.to!int;
  int b = readln.chomp.to!int;
  int maxhp = (1 << (n - 1)), aa, bb;
  aa = (x / a); if (x % a != 0) aa++;
  bb = ((maxhp - x) / b); if ((maxhp - x) % b != 0) bb++;
  if (aa < bb) aa.writeln;
  else bb.writeln;
}