import java.io.InputStream;
import java.io.PrintWriter;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.MathContext;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import java.util.TreeMap;
import java.util.TreeSet;

import static java.util.Comparator.*;

public class Main {
    public static void main(String[] args) {
        PrintWriter out = new PrintWriter(System.out);
        Solver solver = new Solver(System.in, out);
        solver.solve();
        out.close();
    }
}
class Solver {
	Scanner sc;
	PrintWriter out;
    public Solver(InputStream in, PrintWriter out) {
    	sc = new Scanner(in);
    	this.out = out;
    }
    // ==================================================================
    public void solve() {
    	int N = Integer.parseInt(sc.next());
    	int X = Integer.parseInt(sc.next());
    	int A = Integer.parseInt(sc.next());
    	int B = Integer.parseInt(sc.next());
    	int max = 1;
    	for (int i = 0; i < N - 1; i++) {
			max *= 2;
		}
    	int c1 = (X + A - 1) / A;
    	int c2 = (max - X + B - 1) / B;
//    	out.println("A = " + A + "  で　X = " + X + " を処理したら　" + c1);
//    	out.println("B = " + B + "  で　max = " + max + " を処理したら　" + c2);
    	out.println(c1 > c2 ? c2 : c1);
    }
}