#include using namespace std; #define forr(x,arr) for(auto&& x:arr) #define _overload3(_1,_2,_3,name,...) name #define _rep2(i,n) _rep3(i,0,n) #define _rep3(i,a,b) for(int i=int(a);i=int(a);i--) #define rrep(...) _overload3(__VA_ARGS__,_rrep3,_rrep2,)(__VA_ARGS__) #define all(x) (x).begin(),(x).end() #define bit(n) (1LL<<(n)) #define sz(x) ((int)(x).size()) #define TEN(n) ((ll)(1e##n)) #define fst first #define snd second string DBG_DLM(int &i){return(i++==0?"":", ");} #define DBG_B(exp){int i=0;os<<"{";{exp;}os<<"}";return os;} templateostream&operator<<(ostream&os,vectorv); templateostream&operator<<(ostream&os,setv); templateostream&operator<<(ostream&os,queueq); templateostream&operator<<(ostream&os,priority_queueq); templateostream&operator<<(ostream&os,pairp); templateostream&operator<<(ostream&os,mapmp); templateostream&operator<<(ostream&os,unordered_mapmp); templatevoid DBG(ostream&os,TPL t){} templatevoid DBG(ostream&os,TPL t){os<<(I==0?"":", ")<(t);DBG(os,t);} templatevoid DBG(ostream&os,pairp,string delim){os<<"("<ostream&operator<<(ostream&os,tuplet){os<<"(";DBG<0,tuple,Ts...>(os,t);os<<")";return os;} templateostream&operator<<(ostream&os,pairp){DBG(os,p,", ");return os;} templateostream&operator<<(ostream&os,vectorv){DBG_B(forr(t,v){os<ostream&operator<<(ostream&os,sets){DBG_B(forr(t,s){os<ostream&operator<<(ostream&os,queueq){DBG_B(for(;q.size();q.pop()){os<ostream&operator<<(ostream&os,priority_queueq){DBG_B(for(;q.size();q.pop()){os<ostream&operator<<(ostream&os,mapm){DBG_B(forr(p,m){os<");});} templateostream&operator<<(ostream&os,unordered_mapm){DBG_B(forr(p,m){os<");});} #define DBG_OVERLOAD(_1,_2,_3,_4,_5,_6,macro_name,...)macro_name #define DBG_LINE(){char s[99];sprintf(s,"line:%3d | ",__LINE__);cerr<;using pll=pair;using pil=pair;using pli=pair; using vs=vector;using vvs=vector;using vvvs=vector; using vb=vector;using vvb=vector;using vvvb=vector; using vi=vector;using vvi=vector;using vvvi=vector; using vl=vector;using vvl=vector;using vvvl=vector; using vd=vector;using vvd=vector;using vvvd=vector; using vpii=vector;using vvpii=vector;using vvvpii=vector; templatebool amax(A&a,const B&b){return b>a?a=b,1:0;} templatebool amin(A&a,const B&b){return b>l;return l;} string rs(){string s;cin>>s;return s;} void panic() { cout << "Impossible" << endl; exit(0); } void Main() { string s = rs(); sort(all(s)); if (s.back() > 'm') panic(); map C; forr(c, s) C[c]++; bool ok = 1; int ma = 0; rep(i, 13) { if (C['a'+i] != 1) ok = 0; amax(ma, C['a'+i]); } if (ok == 1) { rep(i, 13) cout << (char)('a'+i) << endl; return; } if (ma > 2) panic(); rep(i, 13) { if (C['a'+i] == 0) { cout << (char)('a'+i) << endl; } } } signed main() { cin.tie(nullptr); ios::sync_with_stdio(false); Main(); return 0; }