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

int main() {
  string S;
  cin >> S;
  int ans = 0;
  for (int i = 1; i < S.size(); i++) {
    if (S.at(i) == '3') ans++;
    else {
      ans = -1;
      break;
    }
  }
  cout << ((S.at(0) == '1' && ans) ? ans : -1) << "\n";
}