I don't know why my algo is wrong...
Please help me...
Is there any special test case??

import java.io.*;
class Main {
	
	public static int ISBN(String l, int index) {
		
		int n = l.length();
		int count = 0;
		for (int i = 0; i < n; i ++) {
			
			if (i == index)
				continue;
			
			if (l.charAt(i) == 'X')
				count += 10 * (n - i);
			else
				count += (l.charAt(i) - 48) * (n - i);
		}
		return count;
	}
	
	public static int nextISBN(int sum, int index) {
		
		if (sum % 11 == 0 && sum != 0)
			return 0;
		
		if (sum == 0)
			return 0;
		
		int tmp = 10 - index;
		for (int i = 0; i <= 10; i ++) {
			
			if ((sum + (i * tmp)) % 11 == 0)
				return i;
		}
		return -1;
	}
	
	public static void main(String args[]) throws IOException {
		
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringBuffer buffer = new StringBuffer();
		
		String linea;
		while ((linea = in.readLine()) != null) {
			
			int index = linea.indexOf('?');
			int tmp = ISBN(linea, index);
			int r = nextISBN(tmp, index);
			
			if (r == 10)
				System.out.println('X');
			else
				System.out.println(r);
		}
	}
}