package main

import "fmt"

func pow(b, n int) int {
	//fmt.Printf("pow(%d,%d) en:\n", b, n)
	r := 1
	for i := 0; i < n; i++ {
		r *= b
	}
	// fmt.Printf("pow(%d,%d) ex: %d\n", b, n, r)
	return r
}

func main() {
	var Q int
	fmt.Scan(&Q)
	ans := make([]int, 0)
	for i := 0; i < Q; i++ {
		var N, K int
		fmt.Scan(&N, &K)
		var k int
		if K == 1 {
			k = N - 1
		} else {
			for {
				t := pow(K, k)
				if N-1 <= t {
					break
				}
				k++
			}
		}
		ans = append(ans, k)
	}
	// fmt.Println("ans:", ans)
	for i := 0; i < len(ans); i++ {
		fmt.Println(ans[i])
	}
}