#include<bits/stdc++.h>
#define REP(x,y,z) for(int x=y;x<=z;x++)
#define FORD(x,y,z) for(int x=y;x>=z;x--)
#define MSET(x,y) memset(x,y,sizeof(x))
#define FOR(x,y) for(__typeof(y.begin()) x=y.begin();x!=y.end();x++)
#define F first
#define S second
#define MP make_pair
#define PB push_back
#define SZ size()
#define M 200005
void RI(){}
template<typename... T>
void RI( int& head, T&... tail ) {
    scanf("%d",&head);
    RI(tail...);
}
using namespace std;
typedef long long LL;
int n;
LL x,y,a,b;
int main()
{
	while(~scanf("%d",&n))
	{
		cin >> x >> a >> b;
		y = (1LL<<(n-1)) - x;
		
		LL a1 = x/a + (x%a?1:0);
		LL a2 = y/b + (y%b?1:0);
		cout << min(a1, a2) << endl;
	}
	return 0;
}