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