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 <vector>
#include <iostream>
#include <cmath>
#include <iomanip>
#include <string>
#include <utility>
#include <stack>
#include <numeric>
#include <random>
#include <algorithm>
#include <queue>
#include <functional>
#include <iterator>
#include <list>
#include <unordered_map>
using namespace std;

#define rep(i, b, e) for(i = b; i < e; ++i)
#define repr(i, b, e) for (i = b; i >= e; --i)
#define ull unsigned long long int
#define ll long long int
#define pint pair<int, int>

#define M_DEBUG 1
#define PI 3.141592653589793

#define E '\n'

#define print(x) cout << (x) << endl;
#define printa(x,n) for(int i = 0; i < n; i++){ cout << (x[i]) << "\n";}
#define INF (1e18)

const ll MAX = 1000000000;
const ll MOD = 1e9 + 7;

ull a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z;

ll aabs(ll a) {
    if (a < 0) return -a;
    return a;
}

int main(void) {
    cin >> n >> k;
    l = 1;
    while (1) {
        a = pow(k, l);
        if (a >= n) {
            cout << l << endl;
            break;
        }
        l++;
    }
    

    return 0;
}