#include "bits/stdc++.h"
using namespace std;
using Graph = vector<vector<int>>;
typedef long long ll;
typedef pair<int, int> P;
#define rep(i,n) for (ll i = 0; i < (n); ++i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const long long mod = 1e9 + 7;

ll gcd(ll a, ll b) {
	return b ? gcd(b, a % b) : a;
}

ll lcm(ll a, ll b) {
	return a / gcd(a, b) * b;
}

int main() {
	string n;
	cin >> n;
	
	ll s=n.size();
	ll ans=0;

	if (s == 1) {
		cout << -1 << endl;
		return 0;
	}

	rep(i, s) {
		if ((i == 0 && n[i] != '1') || (i > 0 && n[i] != '3')) {
			cout << -1 << endl;
			return 0;
		} else if (i > 0 && n[i] == '3') {
			ans++;
		}
	}

	cout << ans << endl;
}