#include <algorithm>
#include <iostream>
#include <iomanip>
#include <cstring>
#include <string>
#include <vector>
#include <queue>
#include <cmath>
#include <stack>
#include <set>
#include <map>
typedef long long ll;
typedef unsigned int uint;
using namespace std;

int main() {
	int ans = 0;
	string str;
	long int N;
	cin >> N;

	str = to_string(N);

	if (str[0] != '1'|| 1 == (int)str.size()) {
		cout << -1 << endl;
		return 0;
	}
	for (int i = 1; i < (int)str.size(); i++) {
		if (str[i] == '3') {
			ans++;
		} else {
			cout << -1 << endl;
			return 0;
		}
	}
	cout << ans << endl;
}