#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  vector<int> v(4);
  for (auto &it : v) cin >> it;
  sort(v.begin(), v.end());
  if (v[3] == v[2] + v[1] + v[0])
    cout << "YES" << '\n';
  else if (v[3] + v[0] == v[1] + v[2])
    cout << "YES" << '\n';
  else
    cout << "NO" << '\n';
  return 0;
}
