#include <bits/stdc++.h>
#define int long long
using namespace std;
int n,cnt;
vector<int>a;
vector<int>b;
vector<vector<int>>dp(4005,vector<int>(4,0));
vector<char>s,ans;
void solve(int ind,int t)
{
if(t==0||t==1){s.push_back('A');cnt++;}
else s.push_back('B');
if(s.size()==n&&cnt==n/2)
{
ans=s;
return;
}
if(t==0||t==3)
{
if(dp[ind+1][0])solve(ind+1,0);
if(dp[ind+1][1])solve(ind+1,1);
}
if(t==1||t==2)
{
if(dp[ind+1][2])solve(ind+1,2);
if(dp[ind+1][3])solve(ind+1,3);
}
if(t==0||t==1){s.pop_back();cnt--;}
else s.pop_back();
}
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n;
n*=2;
a.resize(n);
b.resize(n);
for(int i=0;i<n;i++)cin>>a[i];
for(int i=0;i<n;i++)cin>>b[i];
for(int i=0;i<4;i++)dp[n-1][i]=1;
for(int i=n-2;i>=0;i--)
{
if(a[i]<=a[i+1]&&(dp[i+1][0]||dp[i+1][1]))dp[i][0]=1;
if(a[i]<=b[i+1]&&(dp[i+1][3]||dp[i+1][2]))dp[i][1]=1;
if(b[i]<=b[i+1]&&(dp[i+1][2]||dp[i+1][3]))dp[i][2]=1;
if(b[i]<=a[i+1]&&(dp[i+1][0]||dp[i+1][1]))dp[i][3]=1;
}
for(int i=0;i<4;i++)
{
if(dp[0][i])
{
cnt=0;
s.clear();
solve(0,i);
}
if(!ans.empty())break;
}
if(ans.empty())cout<<-1;
else for(auto u:ans)cout<<u;
}
