#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d, sum, h;
  cin >> a >> b >> c >> d;
  sum = a + b + c + d;
  if (sum % 2 == 1)
    cout << "NO" << endl;
  else {
    h = sum / 2;
    if (a == h || b == h || c == h || d == h || a + b == h || a + c == h ||
        a + d == h || b + c == h || b + d == h || c + d == h ||
        a + b + c == h || a + b + d == h || a + c + d == h || b + c + d == h)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
  return 0;
}
