#include using namespace std; typedef long long ll; typedef long double ld; #define REP(i, n) for (int i = 0; i < (n); ++i) #define REPR(i, n) for (int i = n - 1; i >= 0; --i) #define FOR(i, m, n) for (int i = m; i < n; ++i) #define FORR(i, m, n) for (int i = m; i >= n; --i) #define ALL(v) (v).begin(),(v).end() #define ALLR(v) (v).rbegin(),(v).rend() #define fi first #define se second #define PB push_back #define EB emplace_back using P = pair; template using PQ = priority_queue; template using QP = priority_queue,greater>; templatevoid debug(const T &v,ll h,ll w){for(ll i=0;ivoid debug(const T &v,ll n){for(ll i=0;ivoid debug(const vector&v){debug(v,v.size());} templatevoid debug(const vector>&v){for(auto &vv:v)debug(vv,vv.size());} templatevoid debug(stack st){while(!st.empty()){cout<void debug(queue st){while(!st.empty()){cout<void debug(deque st){while(!st.empty()){cout<void debug(PQ st){while(!st.empty()){cout<void debug(QP st){while(!st.empty()){cout<void debug(const set&v){for(auto z:v)cout<void debug(const multiset&v){for(auto z:v)cout<void debug(const array &a){for(auto z:a)cout<void debug(const map&v){for(auto z:v)cout<<"["<bool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (b> s; vector c(26); REP(i,13) c[s[i]-'a']++; int a=0,b=0; REP(i,26){ if(c[i]==2) a++; else if(c[i]==1) b++; } if(a==6&&b==1){ REP(i,26){ if(c[i]==1) cout << char(i+'a') << endl; } } else cout << "Impossible" << endl; }