#include <bits/stdc++.h>
#define int long long
using namespace std;

signed main() {
    string s;
    cin >> s;

    bool f = (s[0] == '1');
    for (int i = 1; i < s.size(); i++) {
        f &= (s[i] == '3');
    }
    cout << (f ? (int)s.size() - 1 : -1) << endl;

    return 0;
}