#include <iostream>
using namespace std;


int main(){
	int e[4];
	int c = 0;
	int d = -1;

	for (auto& x : e) cin >> x;

	for (int i = 0;i < 4;i++){
		for (int j = i+1;j < 4;j++){
			if (e[i] == e[j]){
				e[j] = (d--);
				c++;
				break;
			}
		}
	}

	if (c == 2) cout << "yes" << endl;
	else cout << "no" << endl;

	return 0;
}