#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
ll n;
cin>>n;
ll a[2*n+5],b[2*n+5];
for(ll i=1;i<=2*n;i++){
cin>>a[i];
}
for(ll i=1;i<=2*n;i++){
cin>>b[i];
}
pair<ll,ll>dp[2*n+5][2];
ll bef[2*n+5][2];
memset(bef,-1,sizeof bef);
for(ll i=1;i<=2*n;i++){
for(ll j=0;j<2;j++){
dp[i][j]={-1,-1};
}
}
dp[1][0]={1,1};
dp[1][1]={0,0};
for(ll i=2;i<=2*n;i++){
if((dp[i-1][0].ff!=-1 && a[i-1]<=a[i])&&(dp[i-1][1].ff!=-1 && b[i-1]<=a[i])){
pair<ll,ll>a=dp[i-1][0];
pair<ll,ll>b=dp[i-1][1];
ll l=min(a.ff,b.ff),r=max(a.ss,b.ss);
dp[i][0]={l+1,r+1};
bef[i][0]=2;
}
else if(dp[i-1][0].ff!=-1&&a[i-1]<=a[i]){
dp[i][0]=dp[i-1][0];
dp[i][0].ff++;
dp[i][0].ss++;
bef[i][0]=0;
}
else if(dp[i-1][1].ff!=-1&&b[i-1]<=a[i]){
dp[i][0]=dp[i-1][1];
dp[i][0].ff++;
dp[i][0].ss++;
bef[i][0]=1;
}
if((dp[i-1][0].ff!=-1&&a[i-1]<=b[i])&&(dp[i-1][1].ff!=-1&&b[i-1]<=b[i])){
pair<ll,ll>a=dp[i-1][0];
pair<ll,ll>b=dp[i-1][1];
ll l=min(a.ff,b.ff),r=max(a.ss,b.ss);
dp[i][1]={l,r};
bef[i][1]=2;
}
else if(dp[i-1][0].ff!=-1&&a[i-1]<=b[i]){
dp[i][1]=dp[i-1][0];
bef[i][1]=0;
}
else if(dp[i-1][1].ff!=-1&&b[i-1]<=b[i]){
dp[i][1]=dp[i-1][1];
bef[i][1]=1;
}
}
ll pos=-1;
if(dp[2*n][0].ff<=n&&n<=dp[2*n][0].ss){
pos=0;
}
if(dp[2*n][1].ff<=n&&n<=dp[2*n][1].ss){
pos=1;
}
if(pos==-1){
cout<<-1;
return 0;
}
ll cur=n;
string s="";
for(ll i=2*n;i>=1;i--){
if(pos==0){
s+='A';
cur--;
}
else{
s+='B';
}
if(bef[i][pos]<2){
pos=bef[i][pos];
}
else{
if(dp[i-1][0].ff<=cur&&cur<=dp[i-1][0].ss){
pos=0;
}
else{
pos=1;
}
}
}
reverse(all(s));
cout<<s;
}
