bonApettit.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


public class HelloWorld{
    
    static int bonApetit(int n, int k, int b, int[] arr) {
        int totalCost = 0;
        int bactual = 0;
        // Cuanto costo la cena
        for (int i=0; i < n; i++) {
            if (i != k)
                totalCost += arr[i];
        }
        
        bactual = totalcost/2;
        bactual += arr[k]; // Cuanto debe brian cobrar a anna
        
        int diff = b - bactual;
        boolean sePaso = (diff == 0);
        
        if (sePaso) {
            return diff;
        } else {
            return -1;
        }
    }

     public static void main (String []args) throws IOException {
        //System.out.println("Hello World");
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        
        String line;
        String[] l;
        int[] productCosts;
        
        line = bf.readLine(); //para leer lineas, devuelve strings
        l = line.split(" ");
        int n = Integer.parseInt(l[0]);
        int k = Integer.parseInt(l[1]);
        
        line = bf.readLine();
        l = line.split(" ");
        productCosts = new int[n];
        for (int i = 0; i < n; i++) {
            productCosts[i] = Integer.parseInt(l[i]);
        }
        
        line = bf.readLine();
        int b = Integer.parseInt(line);
        
        int res = bonApetit(n, k, b, productCosts);
        if (res == -1) {
            System.out.println("Bon Appetit");
        } else {
            System.out.println(res);
        }
        
     }
}