/* Author : Mychecksdead */
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define pb push_back
#define all(x) x.begin(), x.end()
#define en cout << '\n'
#define ff first
#define ss second
#define pii pair<int,int>
#define vi vector<int>
const int N = 1e6+100, M = 1e5+10, K = 52, MX = 30;
int n;
array<int, 2> a[N], dp[N][2];
vector<int> g[N][2];
void solve(){
cin >> n;
n *= 2;
for(int i = 1; i <= n; ++i){
cin >> a[i][0];
}
for(int i = 1; i <= n; ++i){
cin >> a[i][1];
}
for(int i = 1; i < n; ++i){
if(a[i + 1][0] >= a[i][0]) g[i][0].pb(0);
if(a[i + 1][1] >= a[i][0]) g[i][0].pb(1);
if(a[i + 1][0] >= a[i][1]) g[i][1].pb(0);
if(a[i + 1][1] >= a[i][1]) g[i][1].pb(1);
}
dp[n][0] = {1, 1};
dp[n][1] = {0, 0};
for(int i = n - 1; i >= 1; --i){
for(int r = 0; r < 2; ++r){
dp[i][r] = {MOD, 0};
for(int u: g[i][r]){
dp[i][r][0] = min(dp[i][r][0], dp[i + 1][u][0] + (r == 0));
dp[i][r][1] = max(dp[i][r][1], dp[i + 1][u][1] + (r == 0));
}
}
}
int st, num = n/2; // current index, state, number of A's
string res;
if(dp[1][0][0] <= n/2 && n/2 <= dp[1][0][1]){
st = 0;
num--;
res += 'A';
}else if(dp[1][1][0] <= n/2 && n/2 <= dp[1][1][1]){
st = 1;
res += 'B';
}else{
cout << -1;
return;
}
for(int i = 2; i <= n; ++i){
for(int u: g[i - 1][st]){
if(dp[i][u][0] <= num && num <= dp[i][u][1]){
st = u;
if(u == 0){
res += 'A';
--num;
}else{
res += 'B';
}
break;
}
}
}
cout << res;
}
int main(){
cin.tie(0); ios::sync_with_stdio(0);
int tt = 1, aa;
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
while(tt--){
solve();
en;
}
cerr<<"time taken : "<<(float)clock()/CLOCKS_PER_SEC<<" seconds\n";
return 0;
}
