#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 + d + b == c)
    cout << "YES";
  else if (a + d + c == b)
    cout << "YES";
  else if (a + b + c == d)
    cout << "YES";
  else if (d + b + c == a)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
