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