#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  vector<int> a(4);
  for (int i = 0; i < 4; i++) cin >> a[i];
  int total = 0;
  for (int i = 0; i < 4; i++) total += a[i];
  int ok = 0;
  for (int mask = 0; mask < (1 << 4); mask++) {
    int sum = 0;
    for (int bit = 0; bit < 4; bit++)
      if ((mask >> bit) & 1) sum += a[bit];
    ok |= (2 * sum == total);
  }
  cout << (ok ? "YES" : "NO") << '\n';
  return 0;
}
