#include <bits/stdc++.h>
using namespace std;
long long max(long long a, long long b) { return (a > b) ? a : b; }
int main() {
  long long n, m, i, j, s = 0, q, k;
  vector<long long> a(4);
  for (i = 0; i < 4; i++) {
    cin >> a[i];
  }
  sort(a.begin(), a.end());
  if (a[0] + a[3] == a[1] + a[2])
    cout << "YES" << endl;
  else if (a[0] + a[1] + a[2] == a[3])
    cout << "YES" << endl;
  else {
    cout << "NO" << endl;
  }
}
