大数加法

import java.math.BigInteger;

import java.util.ArrayList;

import java.util.Scanner;

public class Main{

public static void main(String[] args){

    Scanner input = new Scanner(System.in);

    ArrayList SUM = new ArrayList<>();

    while(true) {

        int n = input.nextInt();

        if(n == 0)break;

        String[] str = new String[n];

        for (int i = 0; i < str.length; i++) {

            str[i] = input.next();

        }

        BigInteger a = new BigInteger(str[0]);

        for (int i = 1; i < str.length; i++) {

            BigInteger b = new BigInteger(str[i]);

            a = a.add(b);

        }

        SUM.add(a);

    }

    for (int i = 0; i < SUM.size(); i++) {

        System.out.println(SUM.get(i));

    }

}

}