#include <bits/stdc++.h>
using namespace std;
void pause() {}
bool sortbysecdesc(const pair<int, int> &a, const pair<int, int> &b) {
  return a.second > b.second;
}
int visited[2005];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int a[4], s = 0;
  for (int i = 0; i < 4; i++) {
    cin >> a[i];
    s += a[i];
  }
  if (a[0] + a[1] == a[2] + a[3] || a[0] + a[2] == a[1] + a[3] ||
      a[1] + a[2] == a[0] + a[3])
    cout << "YES";
  else if (s - a[0] == a[0] || s - a[1] == a[1] || s - a[2] == a[2] ||
           s - a[3] == a[3])
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
