```go
package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	in := bufio.NewReader(os.Stdin)
	out := bufio.NewWriter(os.Stdout)
	defer out.Flush()

	var n, k int
	if _, err := fmt.Fscan(in, &n, &k); err != nil {
		return
	}

	var cnt [101]int
	for i := 0; i < n; i++ {
		var a int
		fmt.Fscan(in, &a)
		cnt[a]++
	}

	m, mx := 0, 0
	for i := 1; i <= 100; i++ {
		if cnt[i] > 0 {
			m++
			if cnt[i] > mx {
				mx = cnt[i]
			}
		}
	}

	d := (mx + k - 1) / k
	ans := k * d * m - n
	fmt.Fprintln(out, ans)
}
```