#include <bits/stdc++.h>
using namespace std;

int main() {
	string s;
	cin >> s;
	
	int len = s.size();
	if (len < 2) {
		cout << -1 << endl;
		return 0;
	}
	int c = 0;
	for (int i = 0; i < len; i++) {
		if (i == 0) {
			if (s.at(i) != '1') {
				cout << -1 << endl;
				return 0;
			}
		}
		else {
			if (s.at(i) == '3') {
				c++;
			}
			else {
				cout << -1 << endl;
				return 0;
			}
		}
	}
	cout << c << endl;


	/*
	int64_t N;
	cin >> N;

	if (N < 13) {
		cout << -1 << endl;
		return 0;
	}

	int c = 0;
	while (N > 0) {
		if (N % 10 == 3) {
			c++;
			N /= 10;

			if (N < 10) {
				if (N == 1) {
					cout << c << endl;
					return 0;
				}
				else {
					cout << -1 << endl;
					return 0;
				}
			}
		}
		else {
			cout << -1 << endl;
			break;
		}
	}
	*/
}