#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
  vector<int> e(4);
  int i;
  for (i = 0; i < e.size(); i++) {
    cin >> e[i];
  }
  sort(e.begin(), e.end());
  cout << (e[0] == e[1] && e[2] == e[3] ? "yes" : "no") << endl;
  return 0;
}

