#include <bits/stdc++.h>
using namespace std;
bool check(string s) {
  string t = s;
  reverse(t.begin(), t.end());
  return (s == t);
}
int main() {
  string s;
  cin >> s;
  int l = 0, r = ((int)s.length()) - 1;
  set<char> all;
  while (l < r) {
    all.insert(s[l]);
    all.insert(s[r]);
    l++;
    r--;
  }
  if (all.size() <= 1) {
    cout << "Impossible" << endl;
    return 0;
  }
  for (int i = 0; i < ((int)s.length()) - 1; i++) {
    string fi = "", se = "";
    for (int j = 0; j <= i; j++) fi += s[j];
    for (int j = i + 1; j < (int)s.length(); j++) se += s[j];
    if (check(se + fi) && (se + fi != s)) {
      cout << 1 << endl;
      return 0;
    }
  }
  cout << 2 << endl;
  return 0;
}
