#include<bits/stdc++.h>
using namespace std ;
typedef long long ll ;
#define MAXN 1000007
int n ;
int a[ MAXN ][ 3 ] ;
int ans[ MAXN ] ;
pair < int , int > dp[ MAXN ][ 3 ] ;
void input ( ) {
cin >> n ;
n *= 2 ;
for ( int i = 1 ; i <= n ; ++ i ) {
cin >> a[ i ][ 1 ] ;
}
for ( int i = 1 ; i <= n ; ++ i ) {
cin >> a[ i ][ 2 ] ;
}
}
void solve ( ) {
for ( int i = 1 ; i <= n ; ++ i ) {
for ( int j = 1 ; j <= 2 ; ++ j ) {
dp[ i ][ j ] = { MAXN , -MAXN } ;
}
}
dp[ 1 ][ 1 ] = { 1 , 1 } ;
dp[ 1 ][ 2 ] = { 0 , 0 } ;
for ( int i = 2 ; i <= n ; ++ i ) {
for ( int j = 1 ; j <= 2 ; ++ j ) {
for ( int t = 1 ; t <= 2 ; ++ t ) {
if ( a[ i ][ j ] >= a[ i - 1 ][ t ] ) {
dp[ i ][ j ].first = min ( dp[ i ][ j ].first , dp[ i - 1 ][ t ].first + ( j == 1 ) ) ;
dp[ i ][ j ].second = max ( dp[ i ][ j ].second , dp[ i - 1 ][ t ].second + ( j == 1 ) ) ;
}
}
}
}
int sr = ( n / 2 ) ;
int x = n , y = -1 ;
if ( dp[ n ][ 1 ].first <= sr && sr <= dp[ n ][ 1 ].second ) { y = 1 ; }
if ( dp[ n ][ 2 ].first <= sr && sr <= dp[ n ][ 2 ].second ) { y = 2 ; }
if ( y == -1 ) {
cout << "-1\n" ;
return ;
}
ans[ x ] = y ;
while ( x > 1 ) {
sr -= ( y == 1 ) ;
if ( a[ x - 1 ][ 1 ] <= a[ x ][ y ] && dp[ x - 1 ][ 1 ].first <= sr && sr <= dp[ x - 1 ][ 1 ].second ) {
y = 1 ;
}
else {
y = 2 ;
}
-- x ;
ans[ x ] = y ;
}
for ( int i = 1 ; i <= n ; ++ i ) {
if ( ans[ 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 ;
}
