#include <iostream>
#include <string>

void solve() {
    std::string s;
    std::cin >> s;

    int ans = s.length() - 1;

    bool ok = ans > 0;
    for (int i = 0; i < (int)s.length(); ++i) {
        if ((i == 0 && s[i] != '1') ||
            (i > 0 && s[i] != '3')) {
            ok = false;
        }
    }

    std::cout << (ok ? ans : -1) << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}