#include<bits/stdc++.h>
using namespace std;

int main()
{
	int a,b,c,d;
	cin>>a>>b>>c>>d;
	if(a==b && c==d)
	{
		cout<<"YES";
	}
	else if(a==c && b==d)
	{
		cout<<"YES";
	}
	else if(a==d && b==c)
	{
		cout<<"YES";
	}
	else
	{
		cout<<"NO";
	}
	return 0;
}