#include <bits/stdc++.h>
using namespace std;
const long long N = 1e4 + 7;
long long n, m, cnt, ans, a, x;
string s;
vector<long long> arr;
pair<long long, long long> p[N];
int main() {
  long long arr[4];
  for (int i = 0; i < 4; i++) {
    cin >> arr[i];
  }
  sort(arr, arr + 4);
  if (arr[0] + arr[3] == arr[2] + arr[1]) {
    cout << "YES";
    return 0;
  }
  if (arr[0] + arr[1] + arr[2] == arr[3]) {
    cout << "YES";
    return 0;
  }
  cout << "NO";
}
