#include <bits/stdc++.h>
using namespace std;
const long long N = 1e6 + 1;
map<long long, long long> mp, pm;
deque<long long> v, vc, ve, vv, vd;
deque<char> p, pe;
deque<string> ts, ss, st;
deque<double> sd, ds;
long long a, b, c, d, e, f, cnt, ans, r, n, l, x, y;
long double q, t, cnt1, cnt2;
string g, h, w, o, m, s;
char z, u;
bool re, rt;
vector<pair<long long, long long> > pr, rp, pp;
map<pair<long long, long long>, long long> aw, wa;
int main() {
  cin.tie(NULL);
  cout.tie(NULL);
  ios_base::sync_with_stdio(0);
  cin >> a >> b >> c >> d;
  v.push_back(a);
  v.push_back(b);
  v.push_back(c);
  v.push_back(d);
  sort(v.rbegin(), v.rend());
  if (v[0] + v[1] == v[2] + v[3]) {
    cout << "YES";
    return 0;
  } else if (v[0] + v[3] == v[2] + v[1]) {
    cout << "YES";
    return 0;
  } else if (v[0] == v[1] + v[2] + v[3]) {
    cout << "YES";
    return 0;
  } else if (v[0] + v[1] + v[2] == v[3]) {
    cout << "YES";
    return 0;
  } else {
    cout << "NO ";
    return 0;
  }
}
