#ifdef LOCAL
#define _GLIBCXX_DEBUG 1
#define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif
#if 0
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
template<class T>
using ordered_set = __gnu_pbds::tree<T, __gnu_pbds::null_type, std::less<T>, __gnu_pbds::rb_tree_tag,
__gnu_pbds::tree_order_statistics_node_update>;
#endif
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstring>
#include <random>
#include <chrono>
#include <cassert>
using namespace std;
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define REP(i,n) for(int (i)=0;(i)<(int)(n);(i)++)
#define each(a,x) for (auto& a: x)
#define tcT template<class T
#define tcTU tcT, class U
#define tcTUU tcT, class ...U
template<class T> using V = vector<T>;
template<class T, size_t SZ> using AR = array<T,SZ>;
typedef string str;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
template<typename T, typename U> T &ctmax(T &x, const U &y){ return x = max<T>(x, y); }
template<typename T, typename U> T &ctmin(T &x, const U &y){ return x = min<T>(x, y); }
mt19937 rng((unsigned)chrono::steady_clock::now().time_since_epoch().count());
#define ts to_string
str ts(char c) { return str(1,c); }
str ts(bool b) { return b ? "true" : "false"; }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
str ts(vector<bool> v) { str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]); res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) { str res = ""; F0R(i,SZ) res += char('0'+b[i]); return res; }
template<class A, class B> str ts(pair<A,B> p);
template<class T> str ts(T v) { bool fst = 1; str res = "{"; for (const auto& x: v) {if (!fst) res += ", "; fst = 0; res += ts(x);} res += "}"; return res;}
template<class A, class B> str ts(pair<A,B> p) {return "("+ts(p.first)+", "+ts(p.second)+")"; }
template<class A> void pr(A x) { cout << ts(x); }
template<class H, class... T> void pr(const H& h, const T&... t) { pr(h); pr(t...); }
void ps() { pr("\n"); }
template<class H, class... T> void ps(const H& h, const T&... t) { pr(h); if (sizeof...(t)) pr(" "); ps(t...); }
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {cerr << ts(h); if (sizeof...(t)) cerr << ", "; DBG(t...); }
tcTU> void re(pair<T,U>& p);
tcT> void re(V<T>& v);
tcT, size_t SZ> void re(AR<T,SZ>& a);
tcT> void re(T& x) { cin >> x; }
void re(double& d) { str t; re(t); d = stod(t); }
void re(long double& d) { str t; re(t); d = stold(t); }
tcTUU> void re(T& t, U&... u) { re(t); re(u...); }
tcTU> void re(pair<T,U>& p) { re(p.first,p.second); }
tcT> void re(V<T>& x) { each(a,x) re(a); }
tcT, size_t SZ> void re(AR<T,SZ>& x) { each(a,x) re(a); }
tcT> void rv(int n, V<T>& x) { x.rsz(n); re(x); }
constexpr bool multitest() {return 0;}
void solve();
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
int t = 1;
if (multitest()) cin >> t;
for (; t; t--) solve();
}
#define SZ 3
void solve() {
int n;
#ifdef LOCAL
n=10000;
#else
re(n);
#endif
if (n == 6) {
ps("ABC.BA");
return;
}
//const ll LIM = 1000000000000ll;
const ll LIM = 1000000000000ll;
vector<ll> v(n);
#ifdef LOCAL
mt19937_64 rng6((unsigned)chrono::steady_clock::now().time_since_epoch().count());
for (int i = 0; i < n; i++) v[i] = uniform_int_distribution(1ll, LIM)(rng6);
#else
re(v);
#endif
sort(all(v));
int pv = 3000;
int bst = 0;
for (int i = 0; i+pv-1 < n; i++) {
if (v[i+pv-1] - v[i] < v[bst+pv-1] - v[bst]) bst = i;
}
dbg(v[bst+pv-1]-v[bst]);
n = pv;
v.erase(v.begin(), v.begin()+bst);
v.erase(v.begin()+n, v.end());
unordered_map<ll, array<ll, 2>> seen;
vi loc(n,-1);
int cnt = 0;
array<int, SZ> arr;
while (1) {
//if ( (sz(gen) + cnt) % 2000000 == 0) dbg(sz(gen), cnt);
int t = 0;
for (int i = 0; i < SZ-1; i++) {
arr[i] = uniform_int_distribution(0, n-i-1)(rng);
}
for (int i = SZ-2; i >= 0; i--) {
for (int j = i+1; j < SZ; j++) if (arr[j] >= arr[i]) arr[j]++;
}
for (int i = 0; i <SZ-1; i++) t += arr[i];
int wa = n/2 * SZ - t;
arr[SZ-1] = uniform_int_distribution(min(n-1, max(0, wa - 30)), max(0, min(n-1, wa+30)))(rng);
sort(all(arr));
for (int i = 0; i < SZ-1; i++) if (arr[i]==arr[i+1]) { cnt++; continue; }
ll arr_i = arr[0]*1ll*n*n + arr[1]*1ll*n + arr[2];
ll tot = 0;
for (int x : arr) tot += v[x];
auto it = seen.insert({tot, {-1, -1}}).first;
auto mark = [&](ll arr, int x) {
int a = arr / n / n;
loc[a]=x;
a = (arr/n)%n;
loc[a]=x;
a = (arr%n);
loc[a]=x;
};
if (it->second[0] != -1) if (it->second[0] == arr_i) { cnt++; continue; }
if (it->second[1] != -1) {
if (it->second[1] == arr_i) { cnt++; continue; }
dbg(it->second);
mark(it->second[0],0);
mark(it->second[1],1);
mark(arr_i,2);
for (int i = 0; i < bst; i++) pr('.');
for (int i = 0; i < n; i++) {
if (loc[i]==-1)pr('.');
else pr((char)('A'+loc[i]));
}
for (int i = 0; i < 10000-n-bst; i++) pr('.');
ps();
//dbg(sz(gen), cnt);
return;
}
if (it->second[0] == -1) it->second[0] = arr_i;
else it->second[1] = arr_i;
}
}