#include <bits/stdc++.h>

using namespace std;

int 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;
  }

}