text: //Vivek Kaushal
  // Bon Apetite
  #include <iostream>
  using namespace std;
  
  double temp = 0.0;
  
  int main () {
      long long int n,q,i;
      cin >> n >> q;
      double A[n];
      for (i = 0; i < n; i++) {
          cin >> A[i];
          if (i != q) temp+=A[i]/2;
      }
      
      double price;
      cin >> price;
      
      if (temp == price)
          cout << "Bon Appetit";
      else
          cout << price - temp;
      return 0;
  }
  