#include <iostream>
#include<stdio.h>
#include<cmath>
using namespace std;

int main()
{
   int a,b,c,d;
   scanf("%d%d%d%d",&a,&b,&c,&d);
   if(abs(a-b)<=d&&abs(b-c)<=d)
        cout<<"YES"<<endl;
    else
        cout<<"NO"<<endl;
    return 0;
}
