#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
using PL = pair<ll, ll>;
// Welcome to my source code!

int main() {
    string s;
    cin >> s;
    if (s[0] != '1') {
        cout << -1 << endl;
        return 0;
    }
    int n = s.size();
    for (int i = 1; i < n; i++) {
        if (s[i] != '3') {
            cout << -1 << endl;
            return 0;
        }
    }
    cout << (n - 1 ? n - 1 : -1) << endl;
}