#include<bits/stdc++.h>
using namespace std;
const int mod=998244353;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int N,A,B,C;
  cin>>N>>A>>B>>C;
  if(A==C){
    cout<<"No\n";
  }else if(A>C){
    cout<<(B<A?"Yes\n":"No\n");
  }else{
    cout<<(B>A?"Yes\n":"No\n");
  }

}