#include <fstream>
#include <iostream>
#include <string>


int main() {

	//std::ifstream inf("Text.txt");	std::cin.rdbuf(inf.rdbuf());

	std::string S;
	std::cin >> S;

	int ans = 0;

	if (S[0] != '1') {
		std::cout << "-1" << std::endl;
		return 0;
	}

	if (S.length() == 1 && S[0] == '1') {
		std::cout << "-1" << std::endl;
		return 0;
	}

	for (unsigned int i = 1; i < S.length(); i++) {
		if (S[i] == '3') {
			ans++;
		}
		else {
			ans = -1;
			break;
		}
	}

	std::cout << ans << std::endl;

	return 0;

}