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