#include <bits/stdc++.h>
#define int long long
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
using namespace std;
const int N=2e3+5;
int a[N*2],b[N*2],dp[N*2][N][2];
signed main(){
ios_base::sync_with_stdio();
cin.tie(0);cout.tie(0);
int n;
cin>>n;
for(int i=1;i<=n*2;i++)cin>>a[i];
for(int i=1;i<=n*2;i++)cin>>b[i];
dp[0][0][0]=1;
for(int i=1;i<=n*2;i++){
for(int j=0;j<=min(i,n);j++){
if(a[i]>=a[i-1]){
dp[i][j][0]=dp[i-1][j][0];
}
if(a[i]>=b[i-1] && !dp[i][j][0]){
dp[i][j][0]=dp[i-1][j][1];
}
if(j-1>=0){
if(b[i]>=a[i-1]){
dp[i][j][1]=dp[i-1][j-1][0];
}
if(b[i]>=b[i-1] && !dp[i][j][1]){
dp[i][j][1]=dp[i-1][j-1][1];
}
}
}
}
int x=n*2,y=n,z=-1;
string res="";
if(dp[n*2][n][1]==1)z=1;
if(dp[n*2][n][0]==1)z=0;
if(z==-1){
cout<<-1<<"\n";
return 0;
}
while(x>=1){
if(z==1){
res+='B';
if(b[x]>=a[x-1] && dp[x-1][y-1][0])z=0;
else z=1;
y--;
}
else{
if(a[x]>=a[x-1] && dp[x-1][y][0])z=0;
else z=1;
res+='A';
}
x--;
}
reverse(all(res));
cout<<res<<"\n";
}
/*
3
0 9
8 1
13 7
*/
