#include<bits/stdc++.h>
#define int long long
using namespace std;
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
cin>>n;
n*=2;
vector<int>a(n+1,0),b(n+1,0);
for(int i=1;i<=n;i++)cin>>a[i];
for(int i=1;i<=n;i++)cin>>b[i];
int dp[n+1][n/2+1][2];
for(int i=0;i<=n;i++)
{
for(int j=0;j<=n/2;j++)
{
dp[i][j][0]=0;
dp[i][j][1]=0;
}
}
dp[0][0][0]=1;
dp[0][0][1]=1;
for(int i=1;i<=n;i++)
{
for(int j=max(0ll,i-(n/2));j<=min(i,n/2);j++)
{
if(j>0)dp[i][j][0]=(a[i-1]<=a[i]&&dp[i-1][j-1][0])||(b[i-1]<=a[i]&&dp[i-1][j-1][1]);
if(j<i)dp[i][j][1]=(a[i-1]<=b[i]&&dp[i-1][j][0])||(b[i-1]<=b[i]&&dp[i-1][j][1]);
}
}
if(dp[n][n/2][0]==0&&dp[n][n/2][1]==0)
{
cout<<-1<<'\n';
return 0;
}
int i=n,k,j=n/2;
vector<char>s;
if(dp[i][j][0]){k=0;s.push_back('A');}
else {k=1;s.push_back('B');}
while(i>1)
{
if(!k)
{
if(b[i-1]<=a[i]&&dp[i-1][j-1][1])k=1;
j--;
}
else
{
if(a[i-1]<=b[i]&&dp[i-1][j][0])k=0;
}
if(k)s.push_back('B');
else {s.push_back('A');}
i--;
}
reverse(s.begin(),s.end());
for(auto u:s)cout<<u;
}
