package main

import "fmt"

func main() {
	var line string
	fmt.Scan(&line)
	first := true
	count := 0
	for _, l := range line {
		s := string(l)
		if first {
			if s != "1" {
				fmt.Println(-1)
				return
			}
			first = false
			continue
		} else {
			if s != "3" {
				fmt.Println(-1)
				return
			} else {
				count++
			}
		}
	}
	fmt.Println(count)
}