#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int a[5], s, p, t;
  cin >> a[0] >> a[1] >> a[2] >> a[3];
  sort(a, a + 4);
  s = a[1] + a[2];
  p = a[0] + a[3];
  t = a[0] + a[1] + a[2];
  if (s == p || t == a[3])
    cout << "YES";
  else
    cout << "NO";
  cout << "\n";
  return 0;
}
