#include<bits/stdc++.h>
#include<fstream>
using namespace std;
#define ll long long
#define pb push_back
#define sz(x) int(x.size())
typedef pair<int,int>ii;
typedef vector<int> vi;
const int mxn=2e3+5;
int n,a[2][2*mxn];
int dp[mxn][mxn][2];
vector<char>ans(2*n+1);
int solve(int i,int j,int k){
if(dp[i][j][k]!=-1)return dp[i][j][k];
if(i>n || j>n)return 0;
if(i+j==2*n){
if(i==n && j==n){
if(ans[i+j]=='$')ans[i+j]=(k==0?'A':'B');
return 1;
}
return 0;
}
int id=i+j;
int ok=0;
if(a[0][id+1]>=a[k][id] && i+1<=n)ok|=solve(i+1,j,0);
if(a[1][id+1]>=a[k][id] && j+1<=n)ok|=solve(i,j+1,1);
if(ok && ans[i+j]=='$')ans[i+j]=(k==0?'A':'B');
return dp[i][j][k]=ok;
}
int32_t main(){
ios_base::sync_with_stdio(0);cin.tie(0);
//setIO("sort");
cin>>n;
for(int i=1;i<=2*n;i++)cin>>a[0][i];
for(int i=1;i<=2*n;i++)cin>>a[1][i];
memset(dp,-1,sizeof(dp));
/*for(int sum=0;sum<2*n;sum++){
for(int j=0;j<=sum;j++){
int i=sum-j;
for(int k=0;k<2;k++){
if(!dp[i][j][k])continue;
if(a[0][sum+1]>=a[k][sum] && i+1<=n)dp[i+1][j][0]=1;
if(a[1][sum+1]>=a[k][sum] && j+1<=n)dp[i][j+1][1]=1;
}
}
}*/
for(int i=0;i<=2*n;i++)ans[i]='$';
solve(0,0,0);
solve(0,0,1);
if(ans[1]=='$'){
cout<<-1<<"\n";
return 0;
}
for(int i=1;i<=2*n;i++)cout<<ans[i];
cout<<"\n";
return 0;
}
