#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll toInt(string s, ll b = 10) {
	assert(b > 1);
	ll res = 0;
	for (char c : s) {
		res *= b;
		res += c - '0';
	}
	return res;
}
string toStr(ll x, ll b = 10) {
	assert(b > 1 && x >= 0);
	if (x == 0) return "0";
	string res;
	while (x) {
		res += (x % b) + '0';
		x /= b;
	}
	reverse(res.begin(), res.end());
	return res;
}
int main() {
	ll n;
	cin >> n;
	map<ll, ll> memo;
	auto f = [&](auto self, ll x) -> ll {
		if (x < 10) return 0;
		if (memo.count(x)) return memo[x];
		string s = toStr(x);
		ll next = 1;
		for (auto c : s) {
			next *= int(c - '0');
		}
		ll res = 1 + self(self, next);
		memo[x] = res;
		return res;
	};
	cout << f(f, n) << endl;
	return 0;
}