#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <iomanip>
#include <sstream>
#include <cstdio>
#include <bitset>
#include <vector>
#include <queue>
#include <cmath>
#include <stack>
#include <set>
#include <map>

#define ft first
#define sd second
#define pb push_back
#define pf push_front
#define mk make_pair
#define all(c) (c).begin(), (c).end()
#define SWS ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define rfile freopen("input.txt", "r", stdin)
#define wfile freopen("output.txt", "w", stdout)
#define files rfile; wfile
#define DEBUG 1

typedef long long ll;
typedef unsigned long long ull;

using namespace std;

const int Z = 3 * (int)1e5 + 111;
const int INF = (int)1e9 + 111;
const int MODF = (int)1e9 + 7;

string ss;

void check(string s, string t) {
  s.erase(s.begin(), s.begin() + t.size());
  s += t;
  if (s != ss) {
    cout << 1 << '\n';
    exit(0);
  }
}

void rec(string s, string t) {
  if (t.size() % 2 != 0 || t.size() == 0)
    return;
  string a = t.substr(0, t.size() / 2);
  string b = t.substr(t.size() / 2 + t.size() % 2, t.size() / 2);
  reverse(b.begin(), b.end());
//  cout << a << '\n' << b << '\n';
//  cout << t.substr(0, t.size() / 2) << '\n';
//  cout << t.substr(t.size() / 2 + t.size() % 2, t.size() / 2) << '\n';
  if (a == b) {

    check(s, a);
    rec(s, a);
  }

}

int main() {
  SWS;
  string s;
  int flag = 0;
  cin >> s;
  ss = s;
  for (int i = 1; i < s.size(); i++)
    if (s[i] != s[i - 1])
      flag = 1;
  if (!flag) {
    cout << "Impossible";
    return 0;
  }
  if (s.size() % 2 == 0) {
    rec(s, s);
    for (int i = 1; i <= s.size() / 2 - s.size() % 2; i++)
      if (s[i] != s[i - 1])
        flag = 1;
    if (!flag) {
      cout << "Impossible";
      return 0;
    }
    cout << 2 << '\n';
    return 0;
  }

  else {
    flag = 0;
    for (int i = 1; i <= s.size() / 2 - s.size() % 2; i++)
      if (s[i] != s[i - 1])
        flag = 1;
    if (!flag) {
      cout << "Impossible";
      return 0;
    }
    cout << 2;
    return 0;
  }
  cout << 3;

  return 0;
}