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