#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long a, b, c, d;
  cin >> a >> b >> c >> d;
  long long sum = a + b + c + d;
  if (sum % 2 == 0) {
    if (a + b == sum / 2 || a + c == sum / 2 || a + d == sum / 2 ||
        b + c == sum / 2 || b + d == sum / 2 || c + d == sum / 2 ||
        a == sum / 2 || b == sum / 2 || c == sum / 2 || d == sum / 2)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  } else
    cout << "NO" << endl;
}
