/** * author: shu8Cream * created: 14.04.2023 22:34:44 **/ #include using namespace std; #define overload3(a,b,c,d,...) d #define rep1(i,n) for (int i=0; i<(n); i++) #define rep2(i,a,n) for (int i=(a); i<(n); i++) #define rep(...) overload3(__VA_ARGS__, rep2, rep1)(__VA_ARGS__) #define rrep1(i,n) for (int i=(n-1); i>=0; i--) #define rrep2(i,a,n) for (int i=(n-1); i>=(a); i--) #define rrep(...) overload3(__VA_ARGS__, rrep2, rrep1)(__VA_ARGS__) #define all(x) (x).begin(), (x).end() #define rall(x) (x).rbegin(), (x).rend() #define sz(x) int((x).size()) #define pcnt __builtin_popcountll using ll = long long; using P = pair; template using vc = vector; template using vv = vc>; using vi = vc; using vvi = vv; const int INF = 1e9; const ll LINF = 8e18; templateistream& operator>>(istream&i,vc&v){rep(j,sz(v))i>>v[j];return i;} templatestring join(const T&v,const string& d=""){stringstream s;rep(i,sz(v))(i?s<ostream& operator<<(ostream&o,const vc&v){if(sz(v))o<istream& operator>>(istream&i,pair&v){return i>>v.first>>v.second;} templateostream& operator<<(ostream&o,const pair&v){return o< inline bool chmax(T& a, T b) {if(a inline bool chmin(T& a, T b) {if(a>b) { a=b;return true; } return false;} // stable sort template vc argsort(const vc &A) { vc ids(sz(A)); iota(all(ids), 0); sort(all(ids), [&](int i, int j) { return (A[i] == A[j] ? i < j : A[i] < A[j]); }); return ids; } // A[I[0]], A[I[1]], ... template vc rearrange(const vc &A, const vc &I) { vc B(sz(I)); rep(i, sz(I)) B[i] = A[I[i]]; return B; } template vc cumsum(vc &A, int off = 1) { vc B(sz(A) + 1); rep(i, sz(A)) B[i + 1] = B[i] + A[i]; if (off == 0) B.erase(B.begin()); return B; } template string to_string(T s); template string to_string(pair p); string to_string(char c) { return string(1, c); } string to_string(string s) { return s; } string to_string(const char s[]) { return string(s); } template string to_string(T v) { if (v.empty()) return "{}"; string ret = "{"; for (auto x : v) ret += to_string(x) + ","; ret.back() = '}'; return ret; } template string to_string(pair p) { return "{" + to_string(p.first) + ":" + to_string(p.second) + "}"; } void debug_out() { cout << endl; } template void debug_out(Head H, Tail... T) { cout << to_string(H) << " "; debug_out(T...); } #ifdef _DEBUG #define debug(...) debug_out(__VA_ARGS__) #else #define debug(...) #endif int main() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); int n; cin >> n; set st; rep(i,n){ string s; cin >> s; st.insert(s); } rep(b,min(10,n)){ string t; if(n-10==0) t=string(n-10,'a'); rep(i,min(10,n)){ if(b>>i&1)t+='a'; else t+='b'; } if(st.count(t))continue; cout<