#include <bits/stdc++.h>
template <typename C>
int sz(const C &c) {
  return c.size();
}
using namespace std;
int main() {
  iostream::sync_with_stdio(false);
  int s = 0;
  vector<int> v(4);
  for (auto &e : v) {
    cin >> e;
    s += e;
  }
  bool r = v[0] + v[1] == v[2] + v[3] || v[0] + v[2] == v[1] + v[3] ||
           v[0] + v[3] == v[1] + v[2] || s - v[0] == v[0] || s - v[1] == v[1] ||
           s - v[2] == v[2] || s - v[3] == v[3];
  cout << (r ? "YES\n" : "NO\n");
}
