#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int arr[4];
int main() {
  for (int 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] ||
      arr[3] + arr[2] == arr[0] + arr[1] || arr[3] + arr[1] == arr[0] + arr[2])
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
