#line 1 "main.cpp"
#include<bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include <debug.hpp>
#define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (static_cast<void>(0))
#endif
//#pragma GCC target("avx,avx2")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pll = pair<ll,ll>;
using pii = pair<int,int>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vul = vector<ull>;
using vpii = vector<pii>;
using vvpii = vector<vpii>;
using vpll = vector<pll>;
using vvpll = vector<vpll>;
using vs = vector<string>;
template<class T> using pq = priority_queue<T,vector<T>, greater<T>>;
#define overload4(_1, _2, _3, _4, name, ...) name
#define overload3(a,b,c,name,...) name
#define rep1(n) for (ll UNUSED_NUMBER = 0; UNUSED_NUMBER < (n); ++UNUSED_NUMBER)
#define rep2(i, n) for (ll i = 0; i < (n); ++i)
#define rep3(i, a, b) for (ll i = (a); i < (b); ++i)
#define rep4(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep1(n) for(ll i = (n) - 1;i >= 0;i--)
#define rrep2(i,n) for(ll i = (n) - 1;i >= 0;i--)
#define rrep3(i,a,b) for(ll i = (b) - 1;i >= (a);i--)
#define rrep4(i,a,b,c) for(ll i = (a) + (((b)-(a)-1) / (c) - (((b)-(a)-1) % (c) && (((b)-(a)-1) ^ c) < 0)) * (c);i >= (a);i -= c)
#define rrep(...) overload4(__VA_ARGS__, rrep4, rrep3, rrep2, rrep1)(__VA_ARGS__)
#define all1(i) begin(i) , end(i)
#define all2(i,a) begin(i) , begin(i) + a
#define all3(i,a,b) begin(i) + a , begin(i) + b
#define all(...) overload3(__VA_ARGS__, all3, all2, all1)(__VA_ARGS__)
#define sum(...) accumulate(all(__VA_ARGS__),0LL)
template<class T> bool chmin(T &a, const T &b){ if(a > b){ a = b; return 1; } else return 0; }
template<class T> bool chmax(T &a, const T &b){ if(a < b){ a = b; return 1; } else return 0; }
template<class T> auto min(const T& a){return *min_element(all(a));}
template<class T> auto max(const T& a){return *max_element(all(a));}
template<class... Ts> void in(Ts&... t);
#define INT(...) int __VA_ARGS__; in(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__; in(__VA_ARGS__)
#define STR(...) string __VA_ARGS__; in(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__; in(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__; in(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__; in(__VA_ARGS__)
#define VEC(type, name, size) vector<type> name(size); in(name)
#define VV(type, name, h, w) vector<vector<type>> name(h, vector<type>(w)); in(name)
ll intpow(ll a, ll b){ll ans = 1; while(b){if(b & 1) ans *= a; a *= a; b /= 2;} return ans;}
ll modpow(ll a, ll b, ll p){ ll ans = 1 % p; a %= p;if(a < 0) a += p;while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; }
bool is_clamp(ll val,ll low,ll high) {return low <= val && val < high;}
void Yes() {cout << "Yes\n";return;}
void No() {cout << "No\n";return;}
void YES() {cout << "YES\n";return;}
void NO() {cout << "NO\n";return;}
template <typename U,typename T>
U floor(U a, T b) {return a / b - (a % b && (a ^ b) < 0);}
// ceil(x,y) = floor(x+y-1,y)なのでx+y-1がoverflowする可能性あり
template <typename U,typename T>
U ceil(U x, T y) {return floor(x + y - 1, y);}
template <typename U,typename T>
T bmod(U x, T y) {return x - y * floor(x, y);}
template <typename U,typename T>
pair<U, T> divmod(U x, T y) {U q = floor(x, y);return {q, x - q * y};}
namespace IO{
#define VOID(a) decltype(void(a))
struct setting{ setting(){cin.tie(nullptr); ios::sync_with_stdio(false);fixed(cout); cout.precision(15);}} setting;
template<int I> struct P : P<I-1>{};
template<> struct P<0>{};
template<class T> void i(T& t){ i(t, P<3>{}); }
void i(vector<bool>::reference t, P<3>){ int a; i(a); t = a; }
template<class T> auto i(T& t, P<2>) -> VOID(cin >> t){ cin >> t; }
template<class T> auto i(T& t, P<1>) -> VOID(begin(t)){ for(auto&& x : t) i(x); }
template<class T, size_t... idx> void ituple(T& t, index_sequence<idx...>){in(get<idx>(t)...);}
template<class T> auto i(T& t, P<0>) -> VOID(tuple_size<T>{}){ituple(t, make_index_sequence<tuple_size<T>::value>{});} 
#undef VOID
}
#define unpack(a) (void)initializer_list<int>{(a, 0)...}
template<class... Ts> void in(Ts&... t){ unpack(IO :: i(t)); }
#undef unpack
constexpr long double PI = 3.141592653589793238462643383279L;
template <class F> struct REC {
    F f;
    REC(F &&f_) : f(forward<F>(f_)) {}
    template <class... Args> auto operator()(Args &&...args) const { return f(*this, forward<Args>(args)...); }};

constexpr int mod = 998244353;
//constexpr int mod = 1000000007;

#line 2 "library/graph/EulerianTrail.hpp"
template<bool directed>
struct EulerianTrail {
    vector<vector<pair<int,int>>> g;
    vector<pair<int,int>> es;
    int M;
    vector<int> used_edge,used_vertex,deg;
    explicit EulerianTrail(int N) : g(N),M(0),used_vertex(N),deg(N) {}
    void add_edge(int u,int v) {
        es.emplace_back(u,v);
        g[u].emplace_back(v,M);
        if(directed) {
            deg[u]++;
            deg[v]--;
        }
        else {
            g[v].emplace_back(u,M);
            deg[u]++;
            deg[v]++;
        }
        M++;
    }
    pair<int,int> get_edge(int idx) {
        assert(0 <= idx && idx < M);
        return es[idx];
    }
    // pair<頂点の順番，辺の順番>
    pair<vector<int>,vector<int>> enumerate_eulerian_trail(int start = -1) {
        if(start == -1) {
            if(directed) {
                start = max_element(deg.begin(),deg.end()) - deg.begin();
                if(deg[start] == 0) {
                    start = (M == 0 ? 0 : es[0].first);
                }
            }
            else {
                for(int i = 0;i < g.size();i++) {
                    if(deg[i] & 1) {
                        start = i;
                        break;
                    }
                }
                if(start == -1) {
                    start = (M == 0 ? 0 : es[0].first);
                }
            }
        }
        if(M == 0) {
            return {{start},{}};
        }
        //辞書順最小
        // for(int i = 0;i < g.size();i++) {
        //     sort(g[i].begin(),g[i].end(),greater());
        // }
        used_edge.assign(M,0);
        vector<pair<int,int>> st;
        vector<int> ord_edge,ord_vertex,D(g.size());
        st.emplace_back(start,-1);
        D[start]++;
        while(!st.empty()) {
            auto [idx,edge_idx] = st.back();
            used_vertex[idx] = 1;
            if(g[idx].empty()) {
                ord_edge.emplace_back(edge_idx);
                ord_vertex.emplace_back(idx);
                st.pop_back();
            }
            else {
                auto e = g[idx].back();
                g[idx].pop_back();
                if(used_edge[e.second]) continue;
                used_edge[e.second] = 1;
                st.emplace_back(e);
                D[idx]--;
                D[e.first]++;
            }
        }
        ord_edge.pop_back();
        reverse(ord_edge.begin(),ord_edge.end());
        reverse(ord_vertex.begin(),ord_vertex.end());
        for(auto &x : D) if(x < 0) {return {{},{}};}
        if(ord_edge.size() != M) {
            return {{},{}};
        }
        return {ord_vertex,ord_edge};
    }   
};
#line 102 "main.cpp"
void solve() {
    int n = 26;
    EulerianTrail<true> ET(2 * n);
    rep(i,n) {
        rep(j,n) {
            ET.add_edge(i,j + n);
            ET.add_edge(j + n,j);
        }
    }
    auto ret = ET.enumerate_eulerian_trail();
    debug(ret.first.size(),26 * 26 * 2);
    rep(i,n * n) {
        cout << char(ret.first[2 * i] + 'A') << char(ret.first[2 * i + 1] - n + 'A') << '\n';
    }
}

int main() {
    int TT = 1;
    //cin >> TT;
    while(TT--) solve();
}