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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
namespace ForAtCoder
{
    class Program
    {
        static void Main()
        {
            string[] str = Console.ReadLine().Split(' ');

            long n = long.Parse(str[0]);
            int k = int.Parse(str[1]);

            try
            {
                string s = Convert.ToString(n, k);

                Console.WriteLine(s.Length);
            }
            catch
            {
                long a = n;
                long mod = 0;
                string rslt = "";

                while (a > 0)
                {
                    mod = a % k;
                    rslt += mod.ToString();

                    a = a / k;
                }

                Console.WriteLine(rslt.Length);
            }
        }
    }
}