#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
using namespace std;
int main() {
	int a, b, c, d, e = 0;
	cin >> a >> b >> c >> d;
	if (a == b) {
		if (c == d) {
			e = 1;
		}
	}
	if (a == c) {
		if (b == d) {
			e = 1;
		}
	}
	if (a == d) {
		if (b == c) {
			e = 1;
		}
	}
	if (e == 0) {
		cout << "no" << endl;
	}
	else {
		cout << "yes" << endl;
	}
	return 0;
}