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