#include <bits/stdc++.h>
#define ll long long
#define str string
#define ins insert
#define ld long double
#define pb push_back
#define pf push_front
#define pof pop_front()
#define pob pop_back()
#define lb lower_bound
#define ub upper_bound
#define endl "\n"
#define fr first
#define sc second
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define sz size()
#define vll vector<ll>
#define bc back()
#define arr array
#define pll vector<pair<ll,ll>>
using namespace std;/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<ll, null_type,less_equal<ll>, rb_tree_tag,tree_order_statistics_node_update>*/
template<class S,class T>
bool chmin(S &a,const T &b) {
return a>b?(a=b)==b:false;
}
template<class S,class T>
bool chmax(S &a,const T &b) {
return a<b?(a=b)==b:false;
}
//void fre(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
void start(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
const ll inf=1e18;
const ll mod=998244353;
const ll N=3e3+7;
const ld eps=1e-9;
ll dp[N][N][2];
void solve(){
ll i,j;
ll n;
cin>>n;
ll a[n*2],b[n*2];
for(i=0;i<n*2;i++)cin>>a[i];
for(i=0;i<n*2;i++)cin>>b[i];
dp[1][0][0]=1;
dp[0][1][1]=1;
for(ll len=1;len<2*n;len++){
for(i=0;i<=len;i++){
j=len-i;
ll x=i+j-1;
if(i>n || j>n) continue;
if(i<n && a[x]<=a[x+1])dp[i+1][j][0]+=dp[i][j][0];
if(j<n && a[x]<=b[x+1])dp[i][j+1][1]+=dp[i][j][0];
if(i<n && b[x]<=a[x+1])dp[i+1][j][0]+=dp[i][j][1];
if(j<n && b[x]<=b[x+1])dp[i][j+1][1]+=dp[i][j][1];
}
}
if(!dp[n][n][0] && !dp[n][n][1]) { cout<<-1<<endl;return; }
ll A=n,B=n,c,x=n*2-1;
if(dp[n][n][0])c=0;
else c=1;
str ans;
while(x){
if(c==0){
ans+='A';
A--;
if(!A || a[x]<a[x-1] || !dp[A][B][0]) c=1;
x--;
}else{
ans+='B';
B--;
if(!B || b[x]<b[x-1] || !dp[A][B][1]) c=0;
x--;
}
}
if(A) ans+='A';
else ans+='B';
reverse(all(ans));
cout<<ans<<endl;
}
signed main(){
start();
ll t=1;
//cin>>t;
while(t--) solve();
return 0;
}
/*
*/
