#define _USE_MATH_DEFINES #pragma region include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include //// //#include // #pragma endregion //#include ///////// #pragma region typedef typedef long long LL; typedef long double LD; typedef unsigned long long ULL; #pragma endregion //typedef ////定数 const int INF = (int)1e9; const LL MOD = (LL)1e9+7; const LL LINF = (LL)4e18+20; const LD PI = acos(-1.0); const double EPS = 1e-9; ///////// using namespace::std; void solve(){ vector hist(26,0); string str; cin>> str; int size = str.size(); for(int i=0;i 2 ){ cout << "Impossible" << endl; return; } if( hist[i]==2 ){ }else if(hist[i]==1){ if( ans==-1 ){ ans = i; }else{ cout << "Impossible" << endl; return; } } } string ansStr = " "; ansStr[0] = 'a'+ans; cout << ansStr << endl; } #pragma region main signed main(void){ std::cin.tie(0); std::ios::sync_with_stdio(false); std::cout << std::fixed;//小数を10進数表示 cout << setprecision(16);//小数点以下の桁数を指定//coutとcerrで別 solve(); } #pragma endregion //main()