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

bool ok (const string &s) {
    const int n = s.length();
    bool ret = (s[0] == '1' and n > 1);
    for (int i = 1; i < n; i++) ret &= (s[i] == '3');
    return ret;
}

int main() {
    string s;
    cin >> s;
    if (not ok(s)) cout << -1 << endl;
    else cout << count_if(s.begin(),s.end(),[](char c){return (c=='3');}) << endl;
    return 0;
}