K-wolf Number

Alice thinks an integer x is a K-wolf number, if every K adjacent digits in decimal representation of x is pairwised different.
Given (L,R,K), please count how many K-wolf numbers in range of [L,R].

The input contains multiple test cases. There are about 10 test cases.

Each test case contains three integers L, R and K.

$1 \leq L \leq R \leq 1e18$
$2 \leq K \leq 5$

For each test case output a line contains an integer.

1 1 2
20 100 5

1
72

ZSTU

2016 Multi-University Training Contest 5