package main

import (
	"fmt"
	"strings"
)

func main() {
	var n string
	fmt.Scan(&n)
	if len(n) == 1 || n[0] != '1' || strings.Count(n, "3") != len(n)-1 {
		fmt.Println("-1")
	} else {
		fmt.Println(strings.Count(n, "3"))
	}
}