#include <bits/stdc++.h>
using namespace std;
long long arr[1000005],brr[1000005];
pair<int,int> can[2][1000005];
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
for(int i=1; i<=2*n; i++) cin >> arr[i];
for(int i=1; i<=2*n; i++) cin >> brr[i];
can[0][0]={0,0}; can[1][0]={0,0};
for(int i=1; i<=2*n; i++){
can[0][i]={1e9,-1};
if(arr[i]>=arr[i-1]){
can[0][i].first=min(can[0][i].first,can[0][i-1].first+1);
can[0][i].second=max(can[0][i].second,can[0][i-1].second+1);
}
if(arr[i]>=brr[i-1]){
can[0][i].first=min(can[0][i].first,can[1][i-1].first+1);
can[0][i].second=max(can[0][i].second,can[1][i-1].second+1);
}
can[1][i]={1e9,-1};
if(brr[i]>=arr[i-1]){
can[1][i].first=min(can[1][i].first,can[0][i-1].first);
can[1][i].second=max(can[1][i].second,can[0][i-1].second);
}
if(brr[i]>=brr[i-1]){
can[1][i].first=min(can[1][i].first,can[1][i-1].first);
can[1][i].second=max(can[1][i].second,can[1][i-1].second);
}
//assert(!(can[0][i].second<can[1][i].first-1||can[0][i].first>can[1][i].second+1));
//cout << can[0][i].first << ' ' << can[0][i].second << " " << can[1][i].first << ' ' << can[1][i].second << '\n';
}
if((can[0][2*n].first>n||can[0][2*n].second<n)&&(can[1][2*n].first>n||can[1][2*n].second<n)){
cout << -1;
return 0;
}
int cur=n,val=1e9;
vector<int> ans;
for(int i=2*n; i>0; i--){
if(arr[i]<=val&&can[0][i].first<=cur&&can[0][i].second>=cur){
cur--;
val=arr[i];
ans.push_back(0);
}
else{
val=brr[i];
ans.push_back(1);
}
}
reverse(ans.begin(),ans.end());
for(int i:ans) cout << (i?'B':'A');
}
