import java.util.Scanner;
public class TGMain {
    
    public static void main(String[] args){
        int a, b, c;
        int v;
        int ans = 0;
        Scanner sc = new Scanner(System.in);
        int[] all = new int[sc.nextInt()];
        for(int i = 0; i < all.length; i++){
            ans += sc.nextInt();
            
        }
        v = sc.nextInt();
        System.out.println(v - ans);
        
    }
}