#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e6+5;
int n,a[N],b[N],dl[N][2],dr[N][2],cnt;
string s;
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin>>n; a[2*n+1]=b[2*n+1]=1e9+1;
for (int i=1; i<=2*n; i++) cin>>a[i];
for (int i=1; i<=2*n; i++) cin>>b[i];
dl[0][0]=dl[0][1]=dr[0][0]=dr[0][1]=0;
for (int i=1; i<=2*n; i++){
dl[i][0]=dl[i][1]=2*n;
dr[i][0]=dr[i][1]=-1;
if (a[i]>=a[i-1]){
dl[i][0]=min(dl[i][0],dl[i-1][0]+1);
dr[i][0]=max(dr[i][0],dr[i-1][0]+1);
}
if (a[i]>=b[i-1]){
dl[i][0]=min(dl[i][0],dl[i-1][1]+1);
dr[i][0]=max(dr[i][0],dr[i-1][1]+1);
}
if (b[i]>=a[i-1]){
dl[i][1]=min(dl[i][1],dl[i-1][0]);
dr[i][1]=max(dr[i][1],dr[i-1][0]);
}
if (b[i]>=b[i-1]){
dl[i][1]=min(dl[i][1],dl[i-1][1]);
dr[i][1]=max(dr[i][1],dr[i-1][1]);
}
}
if (!(dl[2*n][0]<=n && n<=dr[2*n][0]) && !(dl[2*n][1]<=n && n<=dr[2*n][1])){
cout<<-1; return 0;
}
cnt=n;
for (int i=2*n; i>0; i--){
if (dl[i][0]<=cnt && cnt<=dr[i][0] && (s.empty() || (s[(int)s.size()-1]=='A' && a[i]<=a[i+1]) || (s[(int)s.size()-1]=='B' && a[i]<=b[i+1]))){
cnt--; s+="A";
}
else{
s+="B";
}
}
reverse(s.begin(),s.end()); cout<<s;
}
