#include <bits/stdc++.h>
using namespace std;
 
#define REP(i, s, n) for(int i = s; i < n; ++i)
#define rep(i, n)		 REP(i, 0, n)
#define SORT(c)			 sort((c).begin(), (c).end())
#define IINF					INT_MAX
#define LLINF					LLONG_MAX
#define DEBUG					false
 
typedef long long				ll;
typedef pair <int, int> ii;

int main() {
	
	vector<int>a(4);
	rep(i, 4) cin >> a[i];
	SORT(a);
	
	if(a[0] == a[1] && a[2] == a[3]) cout << "yes" << endl;
	else cout << "no" << endl;
	
	return 0;
}