#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base ::sync_with_stdio(false);
  int i;
  vector<int> a(4);
  for (i = 0; i < 4; i++) {
    cin >> a[i];
  }
  sort(a.begin(), a.end());
  if ((a[0] + a[1] + a[2] == a[3]) || (a[0] + a[3] == a[1] + a[2])) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
  return 0;
}
