#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int n;
  cin >> n;
  ll a, b, c;
  cin >> a >> b >> c;
  cout << ((c - a) * (b - a) > 0 ? "Yes" : "No") << endl;
  return 0;
}