#include<iostream>
using namespace std;
int a;
int b;
int c;
int d;
int main(){
	cin >> a;
	cin >> b;
	cin >> c;
	cin >> d;
	if (a == b&&c == d){
		cout << "yes" << endl;
	}
	else if (a == c&&b == d){
		cout << "yes" << endl;
	}
	else if (a == d&&b == c){
		cout << "yes" << endl;
	}
	else cout << "no" << endl;

	return 0;
}