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