#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int s = a + b + c + d;
  if (s % 2 == 0) {
    if (s / 2 - a == b || s / 2 - a == c || s / 2 - a == d || s / 2 == a ||
        s / 2 == b || s / 2 == c || s / 2 == d)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  } else
    cout << "NO" << endl;
  return 0;
}
