Question number: d889 
Question name: Statistics of numbers
Question description: Please calculate the total appearances of the digits in an assigned value
range [L,R].  We ensure that the values will be in the term of 0<L<R<10000.
Example: As in the specified range [2,22] (L=2; R=22) the digit 2 appeared once in the number 2,
once in the number 12, once in the number 20, once in the number 21, and twice in the number 22. 
That gives a total of 6 appearances of the digit 2.

提示：

1. 使用for迴圈。
2. 使用餘數算法：當除以10餘數為2，再除以10，不是餘2結束迴圈 。