#include <iostream>
#include <string>
using namespace std;
int main() {
    string s;
    int i, an = 0;
    cin >> s;
    if ((s[0] != '1') || (s.length() == 1)) {
        an = -1;
    } else {
        for (i = 1; i < s.length(); i++) {
            if (s[i] == '3') {an += 1;}
            else {an = -1; break;}
        }
    }
    cout << an << endl;
    return 0;
}