#include <algorithm> #include <iostream> #include <iomanip> #include <cstring> #include <string> #include <vector> #include <queue> #include <cmath> #include <stack> #include <set> #include <map> typedef long long ll; typedef unsigned int uint; using namespace std; int main() { cin.sync_with_stdio(false); cin.tie(0); cout.tie(0); string s; cin >> s; if (s.size() == 1) { cout << -1 << "\n"; return 0; } if (s[0] != '1') { cout << -1 << "\n"; return 0; } for (int i = 1; i < s.size(); i++) { if (s[i] != '3') { cout << -1 << "\n"; return 0; } } cout << s.size() - 1 << "\n"; return 0; }