package main

import . "fmt"

func main() {
	var n int64
	Scan(&n)
	Println(f(n))
}

func f(x int64) int64 {
	if x < 10 {
		return 0
	}
	var m int64 = 1
	for x > 0 {
		m *= x % 10
		x  /= 10
	}
	return 1 + f(m)
}