#![allow(non_snake_case)]

use std::cmp;
use std::io::{ self, prelude::* };

macro_rules! pick {
    ($tokens:expr) => {
        $tokens.next().unwrap().parse().expect("parse error")
    }
}

fn main() {
    let mut s = String::new();
    io::stdin().read_to_string(&mut s).expect("i/o error");
    let mut tokens = s.split_whitespace();

    let N: u64 = pick!(tokens);
    let X: u64 = pick!(tokens);
    let A: u64 = pick!(tokens);
    let B: u64 = pick!(tokens);

    let t1 = (X+A-1) / A;
    let t2 = (((1<<(N-1))-X)+B-1) / B;
    let ans = cmp::min(t1, t2);

    println!("{}", ans);
}