// Copyright © 2020 Diego Garcia Rodriguez del Campo. All rights reserved.
#include<bits/stdc++.h>
#define INF 1e9
#define MAX 1000005
#define optimiza_io cin.tie(0); ios_base::sync_with_stdio(0);
using namespace std;
typedef long long i64;
int N;
int a[MAX][2];
int dpmn[MAX][2];
int dpmx[MAX][2];
struct node {
int vl, i, j;
bool operator < ( const node & a ) const {
if( vl == a.vl )
return i > a.i;
return vl > a.vl;
}
};
vector < node > q;
void solve( int i , int j , int r ) {
cout << ( j ? 'B' : 'A' );
if( i == N )
return;
// Ir a la A
if( a[i][j] <= a[i + 1][0] &&
dpmn[i + 1][0] <= r &&
dpmx[i + 1][0] >= r )
solve( i + 1 , 0 , r - 1 );
else
solve( i + 1 , 1 , r );
}
int main()
{
optimiza_io
cin >> N;
N *= 2;
for( int j = 0; j < 2; j ++ )
for( int i = 1; i <= N; i ++ ) {
cin >> a[i][j];
dpmx[i][j] = -INF;
dpmn[i][j] = INF;
q.push_back( { a[i][j] , i , j } );
}
sort( q.begin() , q.end() );
for( auto x : q ) {
if( x.i == N ) {
dpmn[x.i][x.j] = dpmx[x.i][x.j] = ! x.j;
continue;
}
dpmn[x.i][x.j] = min( dpmn[x.i + 1][0] , dpmn[x.i + 1][1] ) + ( ! x.j );
dpmx[x.i][x.j] = max( dpmx[x.i + 1][0] , dpmx[x.i + 1][1] ) + ( ! x.j );
}
if( dpmn[1][0] <= N/2 && dpmx[1][0] >= N/2 )
solve( 1 , 0 , N/2 - 1 );
else if( dpmn[1][1] <= N/2 && dpmx[1][1] >= N/2 )
solve( 1 , 1 , N/2 );
else
cout << "-1\n";
return 0;
}
// CHECAR LIMITES
