#include <bits/stdc++.h>
using namespace std;
vector<long long> adj[1000000];
void solve() {
  long long a, b, c, d;
  cin >> a >> b >> c >> d;
  if ((a + b) == (c + d))
    cout << "YES";
  else if ((a + c) == (b + d))
    cout << "YES"
         << "\n";
  else if ((a + d) == (b + c))
    cout << "YES"
         << "\n";
  else if ((a + b + c) == (d))
    cout << "YES"
         << "\n";
  else if ((b + c + d) == a || ((a + c + d) == b) || (a + b + d) == c)
    cout << "YES"
         << "\n";
  else {
    cout << "NO"
         << "\n";
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long test = 0, t;
  t = 1;
  while (test++ < t) {
    solve();
  }
}
