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ZOJ Problem Set - 3436
July Number

Time Limit: 2 Seconds      Memory Limit: 65536 KB

The digital difference of a positive number is constituted by the difference between each two neighboring digits (with the leading zeros omitted). For example the digital difference of 1135 is 022 = 22. The repeated digital difference, or differential root, can be obtained by caculating the digital difference until a single-digit number is reached. A number whose differential root is 7 is also called July Number. Your job is to tell how many July Numbers are there lying in the given interval [a, b].


There are multiple cases. Each case contains two integers a and b. 1 ≤ ab ≤ 109.


One integer k, the number of July Numbers.

Sample Input

1 10

Sample Output


Author: HE, Ningxu
Contest: ZOJ Monthly, November 2010
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