#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int N, M, K;

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