#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const int C = 26;
void add(int &x, int y) {
  x += y;
  while (x >= MOD) x -= MOD;
  while (x < 0) x += MOD;
}
int fix(int x) {
  while (x >= MOD) x -= MOD;
  while (x < 0) x += MOD;
  return x;
}
int pw(int a, int b) {
  int ret = 1;
  while (b) {
    if (b & 1) ret = 1ll * ret * a % MOD;
    b >>= 1;
    a = 1ll * a * a % MOD;
  }
  return ret;
}
const int MAXN = 1e6 + 10;
bool pal(string s) {
  string t = s;
  reverse(t.begin(), t.end());
  return s == t;
}
void solve() {
  string s;
  cin >> s;
  int n = s.size();
  int ans = 10;
  int m = (n + 1) / 2;
  for (int i = m; i + 1 < n; i++) {
    if (s[i] != s[i + 1]) {
      ans = 3 + n % 2;
      break;
    }
  }
  for (int i = 0; i < n / 2; i++) {
    string t = s.substr(0, i + 1);
    if (!pal(t)) {
      ans = 2;
      break;
    }
  }
  for (int i = 1; i < n; i++) {
    string t = s.substr(i) + s.substr(0, i);
    if (t != s && pal(t)) {
      ans = 1;
      break;
    }
  }
  if (ans < 10) {
    cout << ans << "\n";
  } else {
    cout << "Impossible\n";
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int te = 1;
  for (int w = 1; w <= te; w++) {
    solve();
  }
  return 0;
}
