#include <bits/stdc++.h>
using namespace std;
const int MAXN = (int)1e6 + 5;
const int INF = (int)1e9 + 7;
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int a, b, c, d;
  cin >> a >> b >> c >> d;
  if (a + b == c + d or a + c == b + d or a + d == c + b or a + b + c == d or
      a + c + d == b or a + b + d == c or a == b + c + d) {
    cout << "YES";
    return 0;
  }
  cout << "NO";
}
