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