#include <bits/stdc++.h>
using namespace std;
int main() {
  long long Raed[4] = {0};
  for (int i = 0; i < 4; i++) cin >> Raed[i];
  sort(Raed, Raed + 4);
  reverse(Raed, Raed + 4);
  if (Raed[0] + Raed[3] == Raed[2] + Raed[1])
    cout << "YES";
  else if (Raed[3] + Raed[1] + Raed[2] == Raed[0])
    cout << "YES";
  else
    cout << "NO";
}
