#include <iostream>
#include <vector>
#include <utility>
#include <sstream>
#include <climits>
#include <cstring>
#include <algorithm>
#define ll long long
#define ld long double
using namespace std;
const ll mod = 1e9 + 7;
const int maxn = 5e5 + 5, maxn1 = 2e3 + 5;
typedef vector<int> vi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
bool can_construct[maxn1][maxn1][2];
int arr[2 * maxn][2], dp_min[2 * maxn][2], dp_max[2 * maxn][2];
void solve()
{
int n;
cin >> n;
for (int i = 0; i < 2 * n; i++)
{
cin >> arr[i][0];
}
for (int i = 0; i < 2 * n; i++)
{
cin >> arr[i][1];
}
dp_min[0][0] = 0, dp_max[0][0] = 0;
dp_min[0][1] = 1, dp_max[0][1] = 1;
for (int i = 1; i < 2 * n; i++)
{
for (int curr = 0; curr < 2; curr++)
{
dp_min[i][curr] = i + 1;
for (int prev = 0; prev < 2; prev++)
{
if (arr[i][curr] >= arr[i - 1][prev])
{
dp_min[i][curr] = min(dp_min[i][curr], dp_min[i - 1][prev] + curr);
dp_max[i][curr] = max(dp_max[i][curr], dp_max[i - 1][prev] + curr);
}
}
}
}
int curr_arr = -1, n_arr1 = n;
for (int i = 0; i < 2; i++)
{
if (dp_min[2 * n - 1][i] <= n && n <= dp_max[2 * n - 1][i])
{
curr_arr = i;
break;
}
}
if (curr_arr == -1)
{
cout << -1;
return;
}
string ans;
for (int i = 2 * n - 1; i >= 0; i--)
{
ans += (curr_arr ? 'B' : 'A');
for (int nxt = 0; nxt < 2; nxt++)
{
if (i > 0 && arr[i][curr_arr] >= arr[i - 1][nxt] && dp_min[i - 1][nxt] <= n_arr1 - curr_arr && n_arr1 - curr_arr <= dp_max[i - 1][nxt])
{
n_arr1 -= curr_arr;
curr_arr = nxt;
break;
}
}
}
reverse(ans.begin(), ans.end());
cout << ans;
}
int main()
{
// freopen("input_text", "r", stdin);
// freopen("output_text", "w", stdout);
// ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0);
int t = 1;
// cin >> t;
while (t-- > 0)
solve();
}
