#include <bits/stdc++.h>
using namespace std;
void solve() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  if (a == b + c + d) {
    cout << "YES";
    return;
  } else if (a + b == c + d || a + c == b + d || a + d == b + c) {
    cout << "YES";
    return;
  } else if (a + b + c == d || a + b + d == c || a + c + d == b) {
    cout << "YES";
    return;
  } else {
    cout << "NO";
    return;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
  return 0;
}
