#include <bits/stdc++.h>
using namespace std;
long long a[4], b[100], sum = 0, fl = 0;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  for (long long i = 0; i < 4; i++) {
    cin >> a[i];
    sum += a[i];
  }
  if (sum % 2 == 1)
    cout << "NO"
         << "\n";
  else {
    for (long long i = 0; i < 4; i++)
      if (sum - a[i] == sum / 2) fl = 1;
    for (long long i = 0; i < 4; i++)
      for (long long j = 0; j < 4; j++)
        if (i != j && sum - (a[i] + a[j]) == sum / 2) fl = 1;
    if (fl == 1)
      cout << "YES"
           << "\n";
    else
      cout << "NO"
           << "\n";
  }
  return 0;
}
