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