#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int a, b, c, d, m, sum;
  cin >> a >> b >> c >> d;
  sum = a + b + c + d;
  m = max(a, max(b, max(c, d)));
  if (a + b == c + d || a + c == b + d || a + d == b + c)
    cout << "YES";
  else if (m == (sum - m))
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
