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