#include <iostream>
#include <cstdio>
#include <vector>
#include <string>
#include <array>
#include <queue>
#include <deque>
#include <set>
#include <list>
#include <map>
#include <stack>
#include <utility>
#include <algorithm>
#include <numeric>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <cstring>
#include <climits>
#include <bitset>
#include <random>
#include <functional>
#include <sstream>
#include <iomanip>

using namespace std;

#define _CRT_SECURE_NO_WARNINGS
#define rep(i, n) for(int i=0; i<(n); i++)
#define FOR(i, m, n) for(int i=(m);i<(n);i++)
#define SZ(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
#define SORT(x) sort((x).begin(),(x).end())
#define REVE(x) reverse((x).begin(),(x).end())
#define mp make_pair
#define pb push_back

typedef vector<int> VI;
typedef vector<string> VS;
typedef vector<vector<int>> VVI;
typedef pair<int, int> PII;
typedef long long LL;

int main() {
	string s;
	cin >> s;

	string s1 = s;
	sort(all(s1));
	s1.erase(unique(all(s1)), s1.end());

	vector<pair<char, int>> c;
	rep(i, SZ(s1)) {
		c.pb(mp(s1[i], 0));
	}

	rep(i, SZ(s)) {
		rep(j, SZ(s1)) {
			if (s[i] == c[j].first)c[j].second++;
		}
	}

	int c1 = 0, c2 = 0, co = 0;
	rep(i, SZ(s1)) {
		int ci = c[i].second;
		if (ci == 1)c1++;
		else if (ci == 2)c2++;
		else co++;
	}

	if (SZ(c) != 7 || c1 != 1 || co != 0)cout << "Impossible\n";
	else {
		rep(i, SZ(s1)) {
			if (c[i].second == 1)cout << c[i].first << endl;
		}
	}
}