#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#define endl "\n"
#define F first
#define S second
#define pb push_back
//#define int long long
#define in insert
#define mid (l+r)/2
#define in insert
using namespace std;
const int N=2e3+5;
bool dp[2*N][N][2];
int b[2*N],a[2*N],n;
//string ans="";
void get(int id ,int done ,int cur){
if(id==0) return ;
if(cur==0){
if(dp[id-1][done-1][0] && a[id-1]<=a[id]) get(id-1,done-1,0);
else get(id-1,done-1,1);
cout<<'A';
}
else{
if(dp[id-1][done][0] && a[id-1]<=b[id]) get(id-1,done,0);
else get(id-1,done,1);
cout<<'B';
}
return ;
}
int32_t main(){
ios::sync_with_stdio(false);cin.tie(nullptr);
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<=2*n;i++){
for(int j=0;j<=n;j++){
if(dp[i-1][j][0]){
if(a[i-1]<=a[i]) dp[i][j+1][0]=1;
if(a[i-1]<=b[i]) dp[i][j][1]=1;
}
if(dp[i-1][j][1]){
if(b[i-1]<=a[i]) dp[i][j+1][0]=1;
if(b[i-1]<=b[i]) dp[i][j][1]=1;
}
}
}
if(dp[2*n][n][0]+dp[2*n][n][1]==0) cout<<-1;
else{
if(dp[2*n][n][0]==1) get(2*n,n,0);
else get(2*n,n,1);
}
return 0;
}
