#include <bits/stdc++.h>
using namespace std;
int a[100];
int main() {
  ios_base ::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  for (int i = 1; i <= 4; ++i) cin >> a[i];
  sort(a + 1, a + 5);
  cout << ((a[1] + a[4] == a[2] + a[3] || a[1] + a[2] + a[3] == a[4]) ? "YES"
                                                                      : "NO");
  return 0;
}
