#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int flag = 0;
  if ((a + b == c + d) || (a + c == b + d) || (a + d == b + c) ||
      (a == b + c + d) || (b == a + c + d) || (c == b + a + d) ||
      (d == b + c + a)) {
    flag = 1;
  }
  if (flag == 1) {
    cout << "YES";
  } else
    cout << "NO";
  return 0;
}
