package main

import "fmt"

func main() {
	var n string
	fmt.Scan(&n)
	ok := true
	cnt := 0
	if n[0] != '1' || len(n) == 1 {
		ok = false
	} else {
		for i := 1; i < len(n); i++ {
			// fmt.Printf("%s ", string(n[i]))
			if n[i] == '3' {
				cnt++
			} else {
				ok = false
				break
			}
		}
	}
	if ok {
		fmt.Println(cnt)
	} else {
		fmt.Println(-1)
	}
}