import java.math.BigInteger;
import java.util.Scanner;
public class Main
{
    public static void main(String[] args)
    { 
        BigInteger a,b,d;
        String c = "0";
        d = new BigInteger(c);
        Scanner in = new Scanner(System.in);
        while(in.hasNextInt())
        {
            b = d;
            int t = in.nextInt();
            if(t == 0)
                break;
            for(int i=1;i<=t;i++)
            {
                a = in.nextBigInteger();
                b = a.add(b);//注意使用add方法时有返回值！！！
            }
            System.out.println(b);
        }
    }
}