#include <bits/stdc++.h>
using namespace std;
int main() {
  int n = 4, arr[5];
  for (int i = 0; i < n; i++) cin >> arr[i];
  sort(arr, arr + n);
  if (arr[3] == (arr[0] + arr[1] + arr[2]))
    cout << "YES" << endl;
  else if ((arr[0] + arr[3]) == (arr[2] + arr[1]))
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
