//#define __USE_MINGW_ANSI_STDIO 0
#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define IN(a, b, x) (a<=x&&x<b)
#define MP make_pair
#define PB push_back
#define INF (1LL<<30)
#define LLINF (1LL<<60)
#define PI 3.14159265359
#define EPS 1e-12
//#define int ll

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};

int cnt[30];
signed main(void)
{
  string s;
  cin >> s;

  REP(i, s.size()) {
    cnt[s[i]-'a']++;
  }

  int f = 0, g = 0, h = 0, idx;
  REP(i, 13) {
    if(cnt[i] == 0) f++, idx = i;
    if(cnt[i] == 1) g++;
    if(cnt[i] == 2) h++;
  }

  // cout << f << " " << g << " " << h << endl;
  if(g == 13) {
    REP(i, 13) cout << (char)('a'+i) << endl;
  } else if(f == 1 && g == 11 && h == 1) {
    cout << (char)('a'+idx) << endl;
  } else {
    cout << "Impossible" << endl;
  }

  return 0;
}