#include<bits/stdc++.h>
using namespace std;
int main(){

	int a, b, c, d;
	cin>>a>>b>>c>>d;
	if(a == b && c == d || a == c && b == d || a == d || b ==c) cout<<"yes"<<endl;
	else cout<<"no"<<endl;
		
	
	return 0;
}

