#include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define FOR(I,A,B) for(int I = (A); I < (B); ++I) typedef long long ll; int main() { string abc = "abcdefghijklm"; int cnt[13]; FOR(i,0,13) cnt[i] = 0; string s; cin >> s; bool two = false; bool no = false; FOR(i,0,13) { if(s[i]>='a' && s[i]<='m') { cnt[s[i]-'a']++; if(cnt[s[i]-'a'] >= 2 && !two) two = true; else if(cnt[s[i]-'a'] >= 2 && two) { cout << "Impossible" << endl; return 0; } } else { cout << "Impossible" << endl; return 0; } } if(two) { FOR(i,0,13) { if(cnt[i]==0) { cout << abc[i] << endl; return 0; } } } else { FOR(i,0,13) { cout << abc[i] << endl; } } return 0; }