package main

import . "fmt"

func main() {
	var n string
	Scan(&n)
	m:=map[rune]int{}
	for _,c:=range n {
		m[c]++
	}
	if len(m)==2&&n[0]=='1'&&m['1']==1&&m['3']>0 {
		Println(m['3'])
	} else {
		Println(-1)
	}
}