#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;

struct Setup_io {
    Setup_io() {
        ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
        cout << fixed << setprecision(15);
    }
} setup_io;

template <typename T>
inline bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <typename T>
inline bool chmin(T &a, const T &b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

// #include <boost/multiprecision/cpp_bin_float.hpp>
// #include <boost/multiprecision/cpp_int.hpp>
// using namespace boost::multiprecision;

// #include <atcoder>
// using namespace atcoder;
// using mint = modint1000000007;
// using mint = modint998244353;

// const int MOD = 1000000007;
// const int MOD = 998244353;

int main() {
    int N, a, b, c;
    cin >> N >> a >> b >> c;
    if ((a < b && c > a) || (a > b && c < a)) {
        cout << "Yes" << endl;
    } else {
        cout << "No" << endl;
    }
    return 0;
}