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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
#define MOD 1000000007
using namespace std;

typedef long long ll;
#define rep(i,n) for(int i=0;i<n;i++)

long long modinv(long long a, long long m=MOD) {
    long long b = m, u = 1, v = 0;
    while (b) {
        long long t = a / b;
        a -= t * b; swap(a, b);
        u -= t * v; swap(u, v);
    }
    u %= m; 
    if (u < 0) u += m;
    return u;
    /*MODの割り算の際に
    a/＝b;
    を
    a *= modinv(b,MOD);
    とする。
        */
}


int main(){
    int n;
    int k;
    cin >> n >> k;
    int tmp = 1;
    int count = 0;
    while(tmp < n){
        tmp *= k;
        count++;
    }
    if(count==0)cout << 1 << endl;
    else cout << count << endl;
    return 0;
}