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

int main() {
    string s;
    cin >> s;
    int n = s.size();
    bool f = 1 < s.size();
    for (int i = 1; i < n; i++) {
        f &= s[i] == '3';
    }
    if (s[0] == '1' && f) {
        cout << count(s.begin(), s.end(), '3') << endl;
    } else {
        cout << -1 << endl;
    }
    return 0;
}