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

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