#include <bits/stdc++.h>
using namespace std;
int main() {
  int sum = 0;
  vector<int> v(4);
  for (int i = 0; i < 4; ++i) {
    cin >> v[i];
    sum += v[i];
  }
  int sum2;
  bool ok = false;
  for (int i = 0; i < (1 << 4); ++i) {
    sum2 = 0;
    for (int j = 0; j < 4; ++j) {
      if (i & (1 << j)) sum2 += v[j];
    }
    if (sum == 2 * sum2) ok = true;
  }
  if (ok)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
