SOJ 2301 大数+字符串处理

import java.util.*;
import java.math.*;

public class Main {

    public static void main(String[] args) 
    {
        
        Scanner cin = new Scanner(System.in);
        String a,b;
        BigInteger A,B;
        while( cin.hasNext())
        {
            a = cin.next();
            b = cin.next();
            if(a.charAt(0)=='+')
                a = a.substring(1);
            if(b.charAt(0)=='+')
                b = b.substring(1);
            A = new BigInteger(a);
            B = new BigInteger(b);
            A = A.subtract(B);
            System.out.println(A.abs());
        }
    }
}