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 Rust (1.15.1) (judge verdict: Accepted)

use std::io;

fn main() {
    let mut buf = String::new();

    // 1行目の読み込み
    io::stdin().read_line(&mut buf).expect("Failed to read line");
    let vec_1: Vec<&str> = buf.split_whitespace().collect();
    let n: i32 = vec_1[0].parse().unwrap_or(0);
    let k: i32 = vec_1[1].parse().unwrap_or(0);
    
    let mut d = k;
    let mut ans: u32 = 0;

    while d <= n {
        d = d * k;
        ans = ans + 1;
    };

    ans = ans + 1;

    println!("{}", ans);
}