#include <iostream>
#include <cstdlib>
using namespace std;

int main()
{
    long long  x1,x2,y1,y2;
    cin>>x1>>y1>>x2>>y2;
    if (abs(x1-x2)==2){
        if (abs(y1-y2)==1){
            cout <<"YES";
    }
    }
    else if (abs(y1-y2)==2){
        if (abs(x1-x2)==1){
            cout <<"YES";
    }
    }
    else cout <<"NO";
    return 0;
}