#include <iostream>
#include <string>
using namespace std;
int main() {
	string N;
	cin >> N;
	int count = 0;
	if (N.size() == 1)count = -1;
	for (int i = 0; i < N.size(); i++) {
		if (i == 0) {
			if (N[0] != '1') {
				count = -1;
				break;
			}
		}
		if (i >= 1) {
			if (N[i] == '3') {
				count++;
			}
			if (N[i] != '3') {
				count = -1;
				break;
			}
		}
	}
	cout << count << endl;
	return 0;
}