#include<iostream>
#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define IO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
const int N=1e6+3;
int n, dp1[N][2], dp2[N][2], a[N][2];
string ans="";
int solve1(int i, int prej)
{
if(i==2*n+1)
return 0 ;
int &ans=dp1[i][prej];
if(ans!=-1)
return ans ;
ans=20*n;
if(a[i-1][prej]<=a[i][0])
ans=1+min(ans,solve1(i+1,0));
if(a[i-1][prej]<=a[i][1])
ans=min(ans,solve1(i+1,1));
return ans;
}
int solve2(int i, int prej)
{
if(i==2*n+1)
return 0 ;
int &ans=dp2[i][prej];
if(ans!=-1)
return ans ;
ans=-20*n;
if(a[i-1][prej]<=a[i][0])
ans=1+max(ans,solve2(i+1,0));
if(a[i-1][prej]<=a[i][1])
ans=max(ans,solve2(i+1,1));
return ans;
}
void build(int i,int prej, int rem)
{
if(i==2*n+1)
return ;
if(a[i-1][prej]<=a[i][0] && rem-1 >=solve1(i+1,0) && rem-1 <=solve2(i+1,0))
{
//cout<<0;
ans+='A';
build(i+1,0,rem-1);
return ;
}
if(a[i-1][prej]<=a[i][1] && rem >=solve1(i+1,1) && rem <=solve2(i+1,1))
{
ans+='B';
// cout<<1;
build(i+1,1,rem);
return ;
}
}
int main()
{
IO
cin>>n;
for(int j=0; j<2; j++)
for(int i=1; i<=2*n; i++)
cin>>a[i][j];
memset(dp1,-1,sizeof dp1);
memset(dp2,-1,sizeof dp2);
build(1,0,n);
if(ans.size()==2*n)
cout<<ans;
else
cout<<-1;
}
