#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include <debug.h>
#else
#define debug(...)
#endif
#define ft front
#define bk back
#define st first
#define nd second
#define ins insert
#define ers erase
#define pb push_back
#define pf push_front
#define _pb pop_back
#define _pf pop_front
#define lb lower_bound
#define ub upper_bound
#define mtp make_tuple
#define bg begin
#define ed end
#define all(x) (x).bg(), (x).ed()
#define sz(x) (int)(x).size()
typedef long long ll; typedef unsigned long long ull;
typedef double db; typedef long double ldb;
typedef pair<int, int> pi; typedef pair<ll, ll> pll;
typedef vector<int> vi; typedef vector<ll> vll; typedef vector<pi> vpi; typedef vector<pll> vpll;
typedef string str;
template<typename T> T gcd(T a, T b) { return (b == 0? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
#define FOR(i, l, r) for (int (i) = (l); (i) <= (r); ++(i))
#define FOS(i, r, l) for (int (i) = (r); (i) >= (l); --(i))
#define FRN(i, n) for (int (i) = 0; (i) < (n); ++(i))
#define FSN(i, n) for (int (i) = (n) - 1; (i) >= 0; --(i))
#define EACH(i, x) for (auto &(i) : (x))
#define WHILE while
#define file "TEST"
mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
ll rand(ll l, ll r) { return uniform_int_distribution<ll>(l, r)(rd); }
/*
----------------------------------------------------------------
END OF TEMPLATE
----------------------------------------------------------------
Tran The Bao - ghostwriter
Training for VOI23 gold medal
----------------------------------------------------------------
DIT ME CHUYEN BAO LOC
----------------------------------------------------------------
*/
const int oo = 1e9 + 5;
const int N = 1e6 + 5;
int n, a[N], b[N];
pi d[N][2];
void trace(int i, bool z, int j) {
if (i == 0) return;
int nxta = (z? b[i + 1] : a[i + 1]);
if (a[i] <= nxta && d[i - 1][0].st <= j - 1 && j - 1 <= d[i - 1][0].nd) {
trace(i - 1, 0, j - 1);
cout << 'A';
return;
}
trace(i - 1, 1, j);
cout << 'B';
}
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
// freopen(file".inp", "r", stdin);
// freopen(file".out", "w", stdout);
cin >> n;
FOR(i, 1, 2 * n) cin >> a[i];
FOR(i, 1, 2 * n) cin >> b[i];
a[2 * n + 1] = b[2 * n + 1] = oo;
d[0][0] = d[0][1] = {0, 0};
FOR(i, 1, 2 * n)
FOR(j, 0, 1) {
int nxta = (j? b[i + 1] : a[i + 1]);
d[i][j] = {oo, -oo};
if (a[i] <= nxta) {
d[i][j].st = min(d[i][j].st, d[i - 1][0].st + 1);
d[i][j].nd = max(d[i][j].nd, d[i - 1][0].nd + 1);
}
if (b[i] <= nxta) {
d[i][j].st = min(d[i][j].st, d[i - 1][1].st);
d[i][j].nd = max(d[i][j].nd, d[i - 1][1].nd);
}
}
if (d[2 * n][0].nd < n || d[2 * n][0].st > n) {
cout << -1;
return 0;
}
trace(2 * n, 0, n);
return 0;
}
/*
1
2 2
2 2
----------------------------------------------------------------
From Benq:
stuff you should look for
* int overflow, array bounds
* special cases (n=1?)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH
----------------------------------------------------------------
*/
