#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> ti;
typedef vector<ll> li;
typedef vector<li> lii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define LSOne(s) ((s)&(-s))
#define all(x) x.begin(),x.end()
ll INF=1000000000000000010;
int inf=1e9+10;
ll M=1e9+7;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n;cin>>n;
int m=2*n;
vi a(m),b(m);
REP(i,0,m)cin>>a[i];
REP(i,0,m)cin>>b[i];
vector<vector<pi>> dp(m,vector<pi>(2,{inf,-inf}));
dp[0]={{1,1},{0,0}};
REP(i,1,m){
if(a[i-1]<=a[i])dp[i][0]={min(dp[i][0].F,dp[i-1][0].F+1),max(dp[i][0].S,dp[i-1][0].S+1)};
if(a[i-1]<=b[i])dp[i][1]={min(dp[i][1].F,dp[i-1][0].F),max(dp[i][1].S,dp[i-1][0].S)};
if(b[i-1]<=a[i])dp[i][0]={min(dp[i][0].F,dp[i-1][1].F+1),max(dp[i][0].S,dp[i-1][1].S+1)};
if(b[i-1]<=b[i])dp[i][1]={min(dp[i][1].F,dp[i-1][1].F),max(dp[i][1].S,dp[i-1][1].S)};
}
string ans;
if((dp[m-1][0].F<=n&&n<=dp[m-1][0].S)||(dp[m-1][1].F<=n&&n<=dp[m-1][1].S)){
int val;
if(dp[m-1][0].F<=n&&n<=dp[m-1][0].S){
ans.PB('A');
n--;
val=a.back();
}
else{
ans.PB('B');
val=b.back();
}
for(int i=m-2;i>=0;i--){
if(dp[i][0].F<=n&&n<=dp[i][0].S&&a[i]<=val){
ans.PB('A');
n--;
val=a[i];
}
else{
ans.PB('B');
val=b[i];
}
}
}
else{
cout<<-1;
return 0;
}
reverse(ans.begin(),ans.end());
cout<<ans;
}
