#include<iostream>
#include<stdio.h>
using namespace std;
int main()
{
int N,M,x,y;
while(scanf("%d%d%d%d",&N,&M,&x,&y)!=EOF)
if(2*x==N&&2*y==M)
printf("YES\n");
else
printf("NO\n");
}
return 0;