#include<bits/stdc++.h>
using namespace std ;
typedef long long ll ;
#define MAXN 1000007
int n ;
int a[ MAXN ] , b[ MAXN ] ;
int forced[ MAXN ] ;
void input ( ) {
cin >> n ;
n *= 2 ;
for ( int i = 1 ; i <= n ; ++ i ) {
cin >> a[ i ] ;
}
for ( int i = 1 ; i <= n ; ++ i ) {
cin >> b[ i ] ;
}
}
void solve ( ) {
for ( int i = 1 ; i < n ; ++ i ) {
if ( min ( a[ i ] , b[ i ] ) > max ( a[ i + 1 ] , b[ i + 1 ] ) ) {
cout << "-1\n" ;
return ;
}
if ( a[ i ] > a[ i + 1 ] && a[ i ] > b[ i + 1 ] ) {
if ( forced[ i ] == 1 ) {
cout << "-1\n" ;
return ;
}
forced[ i ] = 2 ;
}
if ( b[ i ] > a[ i + 1 ] && b[ i ] > b[ i + 1 ] ) {
if ( forced[ i ] == 2 ) {
cout << "-1\n" ;
return ;
}
forced[ i ] = 1 ;
}
if ( a[ i + 1 ] < a[ i ] && a[ i + 1 ] < b[ i ] ) {
forced[ i + 1 ] = 2 ;
}
if ( b[ i + 1 ] < a[ i ] && b[ i + 1 ] < b[ i ] ) {
forced[ i + 1 ] = 1 ;
}
}
int cnt1 , cnt2 ;
cnt1 = cnt2 = 0 ;
for ( int i = 1 ; i <= n ; ++ i ) {
if ( forced[ i ] == 1 ) { ++ cnt1 ; }
if ( forced[ i ] == 2 ) { ++ cnt2 ; }
}
if ( cnt1 > n / 2 || cnt2 > n / 2 ) {
cout<< "-1\n" ;
return ;
}
vector < pair < ll , int > > v ;
for ( int i = 1 ; i <= n ; ++ i ) {
if ( forced[ i ] == 0 ) {
++ cnt1 , forced[ i ] = 1 ;
v.push_back ( { a[ i ] - b[ i ] , i } ) ;
}
}
sort ( v.begin ( ) , v.end ( ) ) ;
int sz = v.size ( ) ;
for ( int i = 0 ; i < sz ; ++ i ) {
if ( cnt1 == n / 2 ) { break ; }
forced[ v[ i ].second ] = 2 ;
-- cnt1 ;
}
for ( int i = 1 ; i <= n ; ++ i ) {
if ( forced[ i ] == 1 ) { cout << "A" ; }
else { cout << "B" ; }
}
cout << "\n" ;
}
int main ( ) {
//freopen ( "dictionary.in" , "r" , stdin ) ;
ios_base :: sync_with_stdio ( false ) ;
cin.tie ( NULL ) ;
int t = 1 ;
// cin >> t ;
while ( t -- ) {
input ( ) ;
solve ( ) ;
}
return 0 ;
}
