#include <bits/stdc++.h>
using namespace std;
long long a, b, c, d;
int main() {
  ios_base::sync_with_stdio();
  cin.tie(0);
  cout.tie(0);
  cin >> a >> b >> c >> d;
  if (a + b == c + d || a + c == b + d || a + d == c + b || a + b + c == d ||
      a + c + d == b || a + b + d == c || b + c + d == a)
    cout << "YES" << '\n';
  else
    cout << "NO" << '\n';
  return 0;
}
