#define Magic ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long long double
#define en '\n'
#define tsts int tetss; cin >> tetss; while(tetss--)
#define all(a) a.begin() , a.end()
#define pb push_back
#define ld long long double
#define fi first
#define se second
ll INF = 1e18;
const int N = 4e5 + 1;
const int mod = 998244353;
using namespace std;
using namespace __gnu_pbds;
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <typename T>
using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
// order_of_key(n) - The number of items in a set that are strictly smaller than k
// find_by_order(k) - It returns an iterator to the ith largest element
ll lcm(ll a, ll b)
{
ll gc = __gcd(a, b);
return a / gc * b;
}
ll binpow (ll a, ll n) {
if (n == 0)
return 1;
if (n % 2 == 1)
return binpow (a, n-1) * a;
else {
ll b = binpow (a, n/2);
return b * b;
}
}
ll binpow_mod(ll a, ll b, ll md)
{
ll res = 1;
a = a % md;
while (b > 0)
{
if (b & 1)
res = (res * a) % md;
a = (a * a) % md;
b >>= 1;
}
return res;
}
ll in() {ll x; cin >> x; return x;};
ll gcd (ll a, ll b, ll & x, ll & y) {
if (a == 0) {
x = 0; y = 1;
return b;
}
ll x1, y1;
ll d = gcd (b%a, a, x1, y1);
x = y1 - (b / a) * x1;
y = x1;
return d;
}
ll gcdinv(ll a, ll b){
ll x, y;
gcd(a, b, x, y);
return x;
}
ll eql(ll x, ll y, bool ok){
if(ok) return x;
else return y;
}
// -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- чё
ll dp[1000012][2];
ll wh[1000012][2];
void solve(){
ll n; cin >> n;
ll a[2 * n + 12][2];
for(ll i = 1; i <= n * 2; ++i){
for(ll j = 0; j < 2; ++j){
dp[i][j] = INF;
}
}
for(ll i = 1; i <= 2 * n; ++i) cin >> a[i][0];
for(ll i = 1; i <= 2 * n; ++i) cin >> a[i][1];
dp[1][0] = 1;
dp[1][1] = -1;
for(ll i = 2; i <= 2 * n; ++i){
for(ll x = 0; x < 2; ++x){
for(ll y = 0; y < 2; ++y){
ll ch1 = a[i][x];
ll ch2 = a[i - 1][y];
if(ch2 > ch1){
continue;
}
ll nw = dp[i - 1][y];
if(x == 0) nw++;
else nw--;
if(abs(nw) < abs(dp[i][x])){
dp[i][x] = nw;
wh[i][x] = y;
}
}
}
}
if(dp[2 * n][0] == 0){
deque<ll> dq;
ll cur = 0;
for(ll i = 2 * n; i; --i){
dq.push_front(cur);
cur = wh[i][cur];
}
for(auto g : dq){
if(g == 0) cout << 'A';
else cout << 'B';
}
return;
}
if(dp[2 * n][1] == 0){
deque<ll> dq;
ll cur = 1;
for(ll i = 2 * n; i; --i){
dq.push_front(cur);
cur = wh[i][cur];
}
for(auto g : dq){
if(g == 0) cout << 'A';
else cout << 'B';
}
return;
}
cout << -1;
}
int main(){
// freopen("fairphoto.in", "r", stdin); freopen("fairphoto.out", "w", stdout);
Magic
// tsts{
solve();
cout << endl;
// }
}
