#include <bits/stdc++.h>
using namespace std;
int main() {
  int arr[4], i, count1 = 0, count2 = 0, count3 = 0, count4 = 0;
  for (i = 0; i < 4; i++) {
    cin >> arr[i];
  }
  sort(arr, arr + 4);
  count1 = arr[0] + arr[3];
  count2 = arr[1] + arr[2];
  count3 = arr[0] + arr[1] + arr[2];
  count4 = arr[3];
  if ((count1 == count2) || (count3 == count4))
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
