#include <bits/stdc++.h>
using namespace std;
int main() {
  int k;
  vector<int> A;
  for (int i = 0; i < 4; ++i) {
    cin >> k;
    A.push_back(k);
  }
  sort(A.begin(), A.end());
  if (A[0] + A[1] + A[2] == A[3] or A[0] + A[3] == A[1] + A[2]) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
