#include <iostream>
using namespace std;

int main()
{
	int n, a, b, c;
	cin >> n >> a >> b >> c;
	if(c < a){
		if(b >= a) cout << "No" << endl;
		else cout << "Yes" << endl;
	}
	else if(c > a){
		if(b <= a) cout << "No" << endl;
		else cout << "Yes" << endl;
	}
	else cout << "No" << endl;
}