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