#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0), cin.tie(0);
  int arr[4];
  for (int i = 0; i < (int)4; i++) cin >> arr[i];
  sort(arr, arr + 4);
  bool ok = 0;
  for (int mask = 0; mask < (1 << 4); mask++) {
    int sum1 = 0;
    int sum2 = 0;
    for (int bit = 0; bit < 4; bit++) {
      if (mask & (1 << bit)) {
        sum1 += arr[bit];
      } else {
        sum2 += arr[bit];
      }
    }
    if (sum1 == sum2) {
      ok = 1;
      break;
    }
  }
  if (ok)
    cout << "YES" << '\n';
  else
    cout << "NO" << '\n';
  return 0;
}
