#include "stdafx.h"
#include <iostream>
using namespace std;
int main() {
    int stolb, stroka, stolb2, stroka2;
    cin >> stolb >> stroka >> stolb2 >> stroka2;
    //int a = stolb2 - stolb, b = stroka2 - stroka;
    int a = abs(stolb2 - stolb), b = abs(stroka2 - stroka);
    //cout << (((abs (a) + abs (b)) == 3) ? "YES" : "NO");
    cout << (((a == 2 && b == 1) || (a == 1 && b == 2)) ? "YES" : "NO");
    return 0;
}