#include<iostream>
#include<algorithm>
using namespace std;
int main() {
	int a[4];
	cin >> a[0] >> a[1] >> a[2] >> a[3];
	sort(a, a + 4);
	if (a[0] == a[1] & a[2] == a[3]) cout << "yes" << endl;
	else cout << "no" << endl;
}