Problem:
Score : 200 points

Problem Statement

Given is an integer N. Find the number of digits that N has in base K.

Notes

For information on base-K representation, see Positional notation - Wikipedia.

Constraints

All values in input are integers.

1 \leq N \leq 10^9

2 \leq K \leq 10

Input

Input is given from Standard Input in the following format:

N K

Output

Print the number of digits that N has in base K.

Sample Input 1

11 2

Sample Output 1

4

In binary, 11 is represented as 1011.

Sample Input 2

1010101 10

Sample Output 2

7

Sample Input 3

314159265 3

Sample Output 3

18

Solution in Python (3.4.3) (judge verdict: Accepted)

import string
numbers = "0123456789"
alphabets = string.ascii_letters # a-z+A-Zをロード
characters = numbers + alphabets

def base_cvt(value, n=2):
    try:
        tmp = int(value)
    except:
        raise ValueError('Invalid value:', value)
 
    if n < 2 or n > len(characters):
        raise ValueError('Invalid n:', value)
 
    result = ''
    tmp = int(value)
    while tmp >= n:
        idx = tmp%n
        result = characters[idx] + result
        tmp = int(tmp / n)
    idx = tmp%n
    result = characters[idx] + result
    return result
  
a, b = map(int, input().split(" "))

print(len(base_cvt(a,b)))