#include <bits/stdc++.h>
using namespace std;
const double EPS = 0.0000000001;
const long long mod1 = 998244353;
const long long mod2 = 1000000007;
const long long mod3 = 1000000009;
const long long inf = 1000000000000000000;
using namespace std;
signed main() {
  long long a, b, c, d;
  cin >> a >> b >> c >> d;
  vector<long long> v;
  v.push_back(a);
  v.push_back(b);
  v.push_back(c);
  v.push_back(d);
  sort(v.begin(), v.end());
  if (v[3] == v[0] + v[1] + v[2]) {
    cout << "YES";
    return 0;
  }
  if (v[3] + v[2] == v[0] + v[1]) {
    cout << "YES";
    return 0;
  }
  if (v[3] + v[2] + v[1] == v[0]) {
    cout << "YES";
    return 0;
  }
  if (v[3] + v[1] == v[2] + v[0]) {
    cout << "YES";
    return 0;
  }
  if (v[3] + v[0] == v[1] + v[2]) {
    cout << "YES";
    return 0;
  }
  cout << "NO";
}
