// Undone
#include <bits/stdc++.h>
#define int long long
#define double long double
#define INF 1e18
#define MOD 1000000007
using namespace std;
signed main() {
  vector<int> e(4);
  for (int i = 0; i < 4; i++) cin>>e[i];
  sort(e.begin(), e.end());
  if (e[0] == e[1] && e[2] == e[3]) {
    cout << "yes" << endl;
  } else {
    cout << "no" << endl;
  }
}

