#include <bits/stdc++.h>
#define se second
#define fs first
#define mp make_pair
#define pb push_back
#define ll long long
#define ii pair<ll,ll>
#define ld long double
#define SZ(v) (int)v.size()
#define ALL(v) v.begin(), v.end()
#define bit(msk, i) ((msk >> i) & 1)
#define iter(id, v) for(auto id : v)
#define rep(i,m,n) for(int i=(m); i<=(n); i++)
#define reb(i,m,n) for(int i=(m); i>=(n); i--)
using namespace std;
mt19937_64 rd(chrono :: steady_clock :: now().time_since_epoch().count());
ll Rand(ll l, ll r) { return uniform_int_distribution<ll> (l, r)(rd); }
const int N = 1e6 + 7;
const int Mod = 1e9 + 7;
const int szBL = 240;
const int INF = 1e9 + 7;
const int BASE = 137;
int n, m;
int a[2][N];
pair<int,int> f[2][N]; ///nó có thể lấy tối đa đcn
void solution (){
cin >> n;
// n = 20;
rep (i, 1, 2 * n) {
cin >> a[0][i];
// a[0][i]= i;
// cout << a[0][i] << " ";
}
rep (i, 1, 2 * n) {
cin >> a[1][i];
// a[1][i]= Rand(a[0][i], a[0][i]);
}
// cout<<"\n";
// return;
f[0][1] = {1, 1};
f[1][1] = {0, 0};
rep (i, 2, 2 * n)
rep (k, 0, 1) f[k][i] = {INF, -INF};
rep (i, 1, 2 * n - 1) {
rep (k, 0, 1) {
// cout << i <<","<<k<<" "<<f[k][i].fs<<","<<f[k][i].se<<"\n";
rep (t, 0, 1) {
if (t == 0 && a[k][i] <= a[t][i + 1]) {
f[t][i + 1].fs = min(f[t][i + 1].fs, f[k][i].fs + 1);
f[t][i + 1].se = max(f[t][i + 1].se, f[k][i].se + 1);
}
else if (t == 1 && a[k][i] <= a[t][i + 1]) {
f[t][i + 1].fs = min(f[t][i + 1].fs, f[k][i].fs);
f[t][i + 1].se = max(f[t][i + 1].se, f[k][i].se);
}
}
}
}
// cout << f[0][2 * n].fs <<","<<f[0][2 * n].se<<" "<<f[1][2 * n].fs<<","<<f[1][2 * n].se <<"\n";
pair<int,int> u = {-1, -1};
if (f[0][2 * n].se == n) u = {0, 2 * n};
if (f[1][2 * n].se == n) u = {1, 2 * n};
if (u.fs == -1) {
cout << -1 <<"\n";
return;
}
vector<int> vec;
int num0 = n;
while (u.se != 0) {
vec.push_back(u.fs);
// cout << u.fs<<" "<<u.se <<"\n";
if (u.fs == 0) --num0;
rep (k, 0, 1) {
if (a[k][u.se - 1] <= a[u.fs][u.se] && f[k][u.se - 1].fs <= num0 && f[k][u.se - 1].se >= num0) {
u = {k, u.se - 1};
break;
}
}
}
reverse(ALL(vec));
iter (&id, vec) {
if (id == 0) cout <<"A";
else cout <<"B";
}
cout<<"\n";
}
#define file(name) freopen(name".inp", "r", stdin); \
freopen(name".out", "w", stdout);
/*
*/
int main () {
// file("c");
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
ll num_Test = 1;
// cin >> num_Test;
while(num_Test--)
solution();
}
/*
no bug challenge +2
1,0 1,1
1,1 0,0
2,0 1,1
2,1 0,0
3,0 1,2
3,1 0,1
4,0 1,2
4,1 0,1
5,0 1,2
5,1 1000000007,-1000000007
6,0 2,3
6,1 1,2
7,0 0,3
7,1 0,2
8,0 0,4
8,1 0,2
9,0 0,3
9,1 0,4
10,0 0,5
10,1 0,3
11,0 0,4
11,1 0,5
0,6 0,5
*/
