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;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ABC156
{
    class Program
    {
        static void Main(string[] args)
        {
            b();
        }
        
        public static void b()
        {
            int[] nk = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            int l = nk[0];
            int k = nk[1];
            int a = 0;
            bool flg = true;
            string n = "";
            if (nk[1] == 2 || nk[1] == 8 || nk[1] == 10 || nk[1] == 16)
                n = Convert.ToString(nk[0], nk[1]);
            else
            {
                while (flg)
                {
                    n += l % k;
                    a = l / k;
                    l = a;
                    if (a == 0)
                    {
                        flg = false;
                    }
                }
            }
            Console.WriteLine(n.Length);
        }
    }
}