#include<bits/stdc++.h>
using namespace std;
long long a,b,c,d,i,e,f,g,n,m,k,l,wina,darch;
long long A[5][1000006],minn[1000006][5],maxx[1000006][5];
string s;
int main() {
cin>>n;
n*=2;
for(long long i=1;i<=2;i++) {
for(long long j=1;j<=n;j++) {
cin>>A[i][j];
minn[j][i]=1000000009;
}
}
//cout<<"*";
minn[1][1]=1; maxx[1][1]=1;
minn[1][2]=0; maxx[1][2]=0;
for(long long i=1;i<=n;i++) {
for(long long j=1;j<=2;j++) {
//cout<<i<<" "<<j<<endl;
if(A[j][i]>=A[1][i-1]) {
//if(j==1 && i==2) cout<<minn[i][j]<<"-"<<minn[i-1][1]<<endl;
minn[i][j]=min(minn[i][j],minn[i-1][1]+(j==1 ? 1:0));
maxx[i][j]=max(maxx[i][j],maxx[i-1][1]+(j==1 ? 1:0));
}
if(A[j][i]>=A[2][i-1]) {
//if(j==1 & i==2) cout<<minn[i][j]<<"-"<<minn[i-1][2]<<endl;
minn[i][j]=min(minn[i][j],minn[i-1][2]+(j==1 ? 1:0));
maxx[i][j]=max(maxx[i][j],maxx[i-1][2]+(j==1 ? 1:0));
}
}
}
/*for(long long i=1;i<=n;i++) {
for(long long j=1;j<=2;j++) {
cout<<"{"<<minn[i][j]<<" "<<maxx[i][j]<<"}";
}
cout<<endl;
}
cout<<"*";*/
darch=n/2;
wina=1000000009;
for(long long i=n;i>=1;i--) {
for(long long j=1;j<=2;j++) {
if(A[j][i]<=wina && minn[i][j]<=darch && darch<=maxx[i][j]) {
wina=A[j][i];
darch-=(j==1 ? 1:0);
s+=(j==1 ? 'A':'B');
k=1;
break;
}
}
if(k==0) {cout<<-1; return 0; }
}
reverse(s.begin(),s.end());
cout<<s;
}
