#include <bits/stdc++.h>
using namespace std;
const int MX = (int)2e5 + 10;
const int mod = (int)1e9 + 7;
bool check(string& t) {
  bool ok = true;
  int n = t.size();
  for (int j = 0; j < n / 2; ++j) {
    ok &= t[j] == t[n - j - 1];
  }
  return ok;
}
int main(int argc, char* argv[]) {
  cin.tie(0);
  cout.tie(0);
  ios_base::sync_with_stdio(0);
  string s;
  cin >> s;
  int n = s.size();
  int it = 0;
  while (it < n && s[it] == s[0]) it++;
  if (it == n) {
    cout << "Impossible" << endl;
    return 0;
  }
  for (int i = 1; i < n; ++i) {
    string s1 = s.substr(0, i);
    string s2 = s.substr(i);
    string t = s2 + s1;
    if (t != s && check(t)) {
      cout << 1 << endl;
      return 0;
    }
  }
  if (n % 2 == 0) {
    string sx = s.substr(0, n / 2);
    if (!check(sx)) {
      cout << 1 << endl;
      return 0;
    }
  }
  for (int i = 0; i < n / 2; ++i) {
    string sx = s.substr(0, i + 1);
    if (!check(sx)) {
      cout << 2 << endl;
      return 0;
    }
  }
  cout << "Impossible" << endl;
  return 0;
}
