#include <bits/stdc++.h>
using namespace std;
long long fp(long long n, long long p) {
  if (p == 0) return 1;
  if (p == 1) return n % (long long)(1000000007);
  long long res;
  res = fp(n, p / 2) % (long long)(1000000007);
  res = (res * res) % (long long)(1000000007);
  if (p % 2) res = (res * n) % (long long)(1000000007);
  return res;
}
int main() {
  ios::sync_with_stdio(0);
  ios_base::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  ;
  int arr[4];
  for (int i = 0; i < 4; i++) cin >> arr[i];
  int a = 0, b = 0;
  sort(arr, arr + 4);
  do {
    a = 0, b = 0;
    for (int i = 0; i < 4; i++) {
      if (a > b)
        b += arr[i];
      else
        a += arr[i];
    }
    if (a == b) return cout << "YES" << '\n', 0;
  } while (next_permutation(arr, arr + 4));
  cout << "NO" << '\n';
}
