import java.util.*;

class Main{
	static final Scanner s=new Scanner(System.in);

	public static void main(String[] $){
		int n=s.nextInt();
		int r=0;
		for(int i=0;i<n;++i)
			r+=s.nextInt();
		r-=s.nextInt();
		System.out.println(r);
	}
}