#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<int> v(4);
  int sum = 0;
  for (int i = 0; i < 4; i++) {
    cin >> v[i];
  }
  sort(v.begin(), v.end());
  if (v[0] + v[3] == v[1] + v[2] or v[0] + v[1] + v[2] == v[3])
    cout << "YES\n";
  else
    cout << "NO\n";
  return 0;
}
