package main

import (
	"fmt"
	"strings"
)

func main() {
	var n string
	fmt.Scan(&n)
	ok := true
	if n[0] == '1' && len(n) > 1 {
		if strings.ContainsAny(n[1:], "012456789") {
			ok = false
		}
	} else {
		ok = false
	}
	if ok {
		fmt.Println(len(n) - 1)
	} else {
		fmt.Println(-1)
	}
}