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