#include <iostream>
#include <string>

using namespace std;

int main() {
    string s;
    cin >> s;
    if(s[0] != '1' || s.length() == 1) {
        cout << -1 << "\n";
        return 0;
    }
    int ans = 0;
    for(int i=1;i<s.length();++i) {
        if(s[i] == '3') ++ans;
        else {
            cout << -1 << "\n";
            return 0;
        }
    }
    cout << ans << "\n";
    return 0;
}