# include <iostream>
# include <algorithm>
# include <vector>
# include <string>
# include <set>
# include <map>
# include <cmath>
# include <iomanip>
# include <functional>
# include <utility>
# include <stack>
# include <queue>
# include <list>
# include <ctime>
constexpr int MOD = 1000000007;
constexpr int INF = 2000000000;
using namespace std;
int main() {
	int a[4];
	cin >> a[0] >> a[1] >> a[2] >> a[3];

	sort(a, a + 4);
	bool f = (a[0] == a[1]) && (a[2] == a[3]);

	cout << (f ? "yes" : "no") << endl;
}