#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<int> v(4);
  int total = 0;
  for (int i = 0; i < 4; i++) {
    scanf("%d", &v[i]);
    total += v[i];
  }
  sort(v.begin(), v.end());
  do {
    int sum = 0;
    for (int i = 0; i < 4; i++) {
      sum += v[i];
      if (2 * sum == total) {
        cout << "YES";
        return 0;
      }
    }
  } while (next_permutation(v.begin(), v.end()));
  cout << "NO";
  return 0;
}
