#include <bits/stdc++.h>
using namespace std;
struct interval {
int l, r;
interval operator + ( interval x ) const {
return { min( l, x.l ), max( r, x.r ) };
}
interval operator + ( int x ) const {
return { l + x, r + x };
}
};
const int MAX_N = 5e5;
int a[2 * MAX_N + 1], b[2 * MAX_N + 1];
interval dp[2 * MAX_N + 1][2];
int main() {
int n;
cin >> n;
for ( int i = 1; i <= 2 * n; i++ )
cin >> a[i];
for ( int i = 1; i <= 2 * n; i++ )
cin >> b[i];
dp[0][0] = dp[0][1] = { 0, 0 };
for ( int i = 1; i <= 2 * n; i++ ) {
dp[i][0] = { 2 * i, 0 };
if ( a[i] >= a[i - 1] )
dp[i][0] = dp[i][0] + (dp[i - 1][0] + 1);
if ( a[i] >= b[i - 1] )
dp[i][0] = dp[i][0] + (dp[i - 1][1] + 1);
dp[i][1] = { 2 * i, 0 };
if ( b[i] >= a[i - 1] )
dp[i][1] = dp[i][1] + dp[i - 1][0];
if ( b[i] >= b[i - 1] )
dp[i][1] = dp[i][1] + dp[i - 1][1];
}
if ( !((dp[2 * n][0].l <= n && n <= dp[2 * n][0].r) || (dp[2 * n][1].l <= n && n <= dp[2 * n][1].r)) ) {
cout << -1;
return 0;
}
vector<char> sol;
int j = n, lastt = 1e9;
for ( int i = 2 * n; i >= 1; i-- ) {
if ( dp[i][0].l <= j && j <= dp[i][0].r && a[i] <= lastt ) {
sol.push_back( 'A' );
lastt = a[i];
j--;
} else {
sol.push_back( 'B' );
lastt = b[i];
}
}
reverse( sol.begin(), sol.end() );
for ( char c: sol )
cout << c;
return 0;
}
