```go
package main

import (
	"fmt"
	"strconv"
)

func main() {
	var n, k int
	fmt.Scan(&n, &k)

	s := strconv.Itoa(n)
	zeros := 0
	ans := len(s) - 1

	for i := len(s) - 1; i >= 0; i-- {
		if s[i] == '0' {
			zeros++
		}
		if zeros == k {
			ans = len(s) - i - k
			break
		}
	}

	fmt.Println(ans)
}
```