#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
//const long nPrime = 1000000007;
//const long nPrime = 998244353;
typedef long long ll;
int main() {
    long n,a,b,c;
    cin >> n >> a >> b >> c;
    if(a==c){
        cout << "No" << endl;
        return 0;
    }
    
    if((a > c && a < b) || (a < c && a > b)){
        cout << "No" << endl;
        return 0;
    }
    cout << "Yes" << endl;
    return 0;
}