#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int arr[4];
  long long int sum = 0;
  for (long long int i = 0; i < 4; i++) {
    cin >> arr[i];
    sum += arr[i];
  }
  if (sum % 2 == 1) {
    cout << "NO";
    return 0;
  }
  sort(arr, arr + 4);
  if (arr[0] + arr[3] == arr[1] + arr[2]) {
    cout << "YES";
  } else if (arr[0] + arr[1] + arr[2] == arr[3]) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
