// EXPLOSION!
#define _CRT_SECURE_NO_WARNINGS
#include<bits/stdc++.h>
#include<unordered_set>
#include<unordered_map>
#include<chrono>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pair<int, int>> vpi;
typedef vector<pair<ll, ll>> vpll;
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)
#define pb push_back
#define mp make_pair
#define rsz resize
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define f first
#define s second
#define cont continue
//#define endl '\n'
//#define ednl '\n'
#define test int testc;cin>>testc;while(testc--)
#define pr(a, b) trav(x,a)cerr << x << b; cerr << endl;
#define message cout << "Hello World" << endl;
const int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 }; // for every grid problem!!
const ll linf = 4000000000000000000LL;
const ll inf = 1000000007;//998244353
void pv(vi a) { trav(x, a)cout << x << " "; cout << endl; }void pv(vll a) { trav(x, a)cout << x << " "; cout << endl; }void pv(vector<vi>a) {
F0R(i, sz(a)) { cout << i << endl; pv(a[i]); cout << endl; }
}void pv(vector<vll>a) { F0R(i, sz(a)) { cout << i << endl; pv(a[i]); }cout << endl; }void pv(vector<string>a) { trav(x, a)cout << x << endl; cout << endl; }
void setIO(string s) {
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef arwaeystoamneg
if (sz(s))
{
freopen((s + ".in").c_str(), "r", stdin);
if (s != "test1")
freopen((s + ".out").c_str(), "w", stdout);
}
#endif
}
struct T
{
int a, b;
void operator+=(const T& x)
{
a = min(a, x.a);
b = max(b, x.b);
}
T()
{
a = inf, b = -inf;
}
T(int x, int y)
{
a = x, b = y;
}
T operator+(int x)const
{
T res = T(a, b);
res.a += x, res.b += x;
return res;
}
bool check(int x)
{
return a <= x && x <= b;
}
};
int n;
vi a, b;
int main()
{
setIO("test1");
cin >> n;
a.rsz(2 * n);
b.rsz(2 * n);
trav(x, a)cin >> x;
trav(x, b)cin >> x;
a.pb(inf);
b.pb(inf);
vector<T> A(2 * n + 1), B(2 * n + 1);
A[0] = T(1, 1);
B[0] = T(0, 0);
F0R(i, 2 * n)
{
// A -> A
if (a[i] <= a[i + 1])
A[i + 1] += (A[i] + 1);
// A -> B
if (a[i] <= b[i + 1])
B[i + 1] += A[i];
// B -> A
if (b[i] <= a[i + 1])
A[i + 1] += (B[i] + 1);
// B -> B
if (b[i] <= b[i + 1])
B[i + 1] += B[i];
}
if (min(A[2 * n - 1].a, B[2 * n - 1].a) > n || n > max(A[2 * n - 1].b, B[2 * n - 1].b))
{
cout << -1 << endl;
return 0;
}
int pos = 'A', c = n;
if (!A[2 * n - 1].check(n))pos = 'B';
string ans = "";
R0F(i, 2 * n - 1)
{
ans.pb(pos);
if (pos == 'A')
{
c--;
if (a[i] <= a[i + 1])
{
if ((A[i]).check(c))
{
}
else
{
pos = 'B';
}
}
else
{
pos = 'B';
}
}
else
{
if (a[i] <= b[i + 1])
{
if ((A[i]).check(c))
{
pos = 'A';
}
}
else
{
}
}
}
ans.pb(pos);
reverse(all(ans));
cout << ans << endl;
}
