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;

using System.Globalization;

namespace AtCoder
{
    class Program
    {
        public static void Main()
        {
            string[] str = Console.ReadLine().Split(' ');
            double N = double.Parse(str[0]);
            double K = double.Parse(str[1]);
            double ans = 0;
            double i = 30;

            while(i >= 0)
            {
                if(N >= Math.Pow(K,i))
                {
                    ans = i;
                    ans++;
                    break;
                }

                i--;
            }
            Console.WriteLine("{0}", ans);
        }   
    }
}