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

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