```go
package main

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

func main() {
	in := bufio.NewReader(os.Stdin)

	var n string
	var k int
	fmt.Fscan(in, &n, &k)

	if n == "0" {
		fmt.Println(0)
		return
	}

	zeros := 0
	deletions := 0

	for i := len(n) - 1; i >= 0; i-- {
		if n[i] == '0' {
			zeros++
			if zeros == k {
				fmt.Println(deletions)
				return
			}
		} else {
			deletions++
		}
	}

	fmt.Println(len(n) - 1)
}
```