Problem:
Score : 500 points

Problem Statement

Find the number of integers between 1 and N (inclusive) that contains exactly K non-zero digits when written in base ten.

Constraints

1 \leq N < 10^{100}

1 \leq K \leq 3

Input

Input is given from Standard Input in the following format:

N
K

Output

Print the count.

Sample Input 1

100
1

Sample Output 1

19

The following 19 integers satisfy the condition:

1,2,3,4,5,6,7,8,9,10,20,30,40,50,60,70,80,90,100

Sample Input 2

25
2

Sample Output 2

14

The following 14 integers satisfy the condition:

11,12,13,14,15,16,17,18,19,21,22,23,24,25

Sample Input 3

314159
2

Sample Output 3

937

Sample Input 4

9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999
3

Sample Output 4

117879300

Solution in Haskell (GHC 7.10.3) (judge verdict: Wrong Answer)

main=do
 n<-getLine
 k<-readLn
 print$f n k
f n k
 |k==0=1
 |null n=0
 |head n=='0'=0
 |otherwise=(f(tail n)(k-1))+(f s(k-1))*(l-1)+f s k
  where s=map(const '9')$tail n
        l=subtract 48$fromEnum$head n