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

#define int long long

void out(vector<int> a) {
    for (int i = 0; i<a.size(); ++i) cout << a[i] << " ";
    cout << "\n";
    return;
}

signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cout << fixed << setprecision(20);
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);

    string s;
    map<char, int> mp;
    cin >> s;

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

    return 0;
}