#include <bits/stdc++.h>
using namespace std;
int main() {
  int arr[4];
  cin >> arr[0] >> arr[1] >> arr[2] >> arr[3];
  sort(arr, arr + 4);
  if ((arr[0] + arr[3]) == (arr[1] + arr[2]) ||
      (arr[0] + arr[1] + arr[2]) == arr[3]) {
    cout << "YES" << '\n';
  } else {
    cout << "NO" << '\n';
  }
  return 0;
}
