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