#include <bits/stdc++.h>
using namespace std;
void minself(int& x,int val){
if(x>val)
x=val;
}
void maxself(int& x,int val){
if(x<val)
x=val;
}
int const MAX=1e6+5;
int n;
int mat[2][MAX];
int le[2][MAX],ri[2][MAX];
void read(){
cin>>n;
int i,j;
for(i=0;i<2;++i)
for(j=1;j<=2*n;++j)
cin>>mat[i][j];
}
void get_dp(){
int i,j;
for(j=1;j<=2*n;++j)
for(i=0;i<2;++i){
le[i][j]=1e9;
ri[i][j]=-1e9;
int lin;
for(lin=0;lin<2;++lin)
if(mat[lin][j-1]<=mat[i][j]){
minself(le[i][j],le[lin][j-1]);
maxself(ri[i][j],ri[lin][j-1]);
}
if(i==0){
++le[i][j];
++ri[i][j];
}
}
}
void write_path(int lin,int col,int cnt){
if(col==0)
return;
int i;
for(i=0;i<2;++i)
if(mat[i][col-1]<=mat[lin][col] && le[i][col-1]<=cnt-(lin==0) && cnt-(lin==0)<=ri[i][col-1]){
write_path(i,col-1,cnt-(lin==0));
break;
}
cout<<((lin==0)?'A':'B');
}
void write(){
int i;
for(i=0;i<2;++i)
if(le[i][2*n]<=n && n<=ri[i][2*n]){
write_path(i,2*n,n);
return;
}
cout<<-1;
}
int main()
{
read();
get_dp();
write();
return 0;
}
