#include<bits/stdc++.h>
#define pb push_back
#define ii pair<int,int>
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define INF 100000000000000000
#define modulo 1000000007
#define mod 998244353
#define int long long int
using namespace std;
#define iii pair<ii, int>
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n; n *= 2;
vector<iii> arr;
for(int i = 0; i < n; i++){
int x;
cin >> x;
arr.pb({{x, i}, 1});
}
for(int i = 0; i < n; i++){
int x;
cin >> x;
arr.pb({{x, i}, -1});
}
sort(all(arr));
vector<int> L, R;
int l = 0;
for(int i = 0; i < n; i++){
while(l < sz(arr) && i != arr[l].first.second) l++;
if(l == sz(arr)){
cout << -1;
return 0;
}
L.pb(l);
}
int r = sz(arr) - 1;
for(int i = n - 1; i >= 0; i--){
while(i != arr[r].first.second) r--;
R.pb(r);
}
reverse(all(R));
vector<vector<int> > Lgrp, Rgrp;
vector<ii> range;
vector<int> tl, tr;
l = 0, r = 0;
while(l < sz(L) && r < sz(R)){
tl.clear(), tr.clear();
int sum = 0;
int mn, mx;
do{
if(l != sz(L) && (r == sz(R) || L[l] <= R[r])){
sum++;
tl.pb(L[l++]);
}
else{
sum--;
tr.pb(R[r++]);
}
}while(sz(tl) != sz(tr));
for(auto p : tl){
sum += arr[p].second;
}
mn = mx = sum;
for(int i = sz(tl) - 1; i >= 0; i--){
sum -= arr[tl[i]].second;
sum += arr[tr[i]].second;
mn = min(mn, sum);
mx = max(mx, sum);
}
Lgrp.pb(tl);
Rgrp.pb(tr);
range.pb({mn, mx});
}
vector<int> g;
int S = 0;
for(auto p : range) S += p.first, g.pb(p.first);
if(S > 0 || (S + INF) % 2){
cout << -1;
return 0;
}
l = 0;
for(int i = 0; i < sz(range); i++){
int c = min(range[i].second - range[i].first, -S);
S += c;
g[i] += c;
}
if(S < 0){
cout << -1;
return 0;
}
vector<int> ans(n);
for(int i = 0; i < sz(range); i++){
int sum = 0;
for(int j = sz(Lgrp[i]) - 1; j >= 0; j--){
ans[arr[Lgrp[i][j]].first.second] = arr[Lgrp[i][j]].second;
sum += arr[Lgrp[i][j]].second;
}
for(int j = sz(Lgrp[i]) - 1; j >= 0 && sum != g[i]; j--){
sum -= arr[Lgrp[i][j]].second;
sum += arr[Rgrp[i][j]].second;
ans[arr[Lgrp[i][j]].first.second] = arr[Rgrp[i][j]].second;
}
}
for(int i = 0; i < n; i++) cout << (ans[i] == 1 ? 'A' : 'B');
}
