#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 a[2 * maxn], b[2 * maxn];
void solve()
{
int n;
cin >> n;
for (int i = 0; i < 2 * n; i++)
{
cin >> a[i];
}
for (int i = 0; i < 2 * n; i++)
{
cin >> b[i];
}
can_construct[1][0][0] = can_construct[0][1][1] = 1;
for (int i = 0; i <= n; i++)
{
for (int j = 0; j <= n; j++)
{
if (i + j < 2)
continue;
if (i > 1)
can_construct[i][j][0] |= can_construct[i - 1][j][0] && a[i + j - 1] >= a[i + j - 2];
if (j > 1)
can_construct[i][j][1] |= can_construct[i][j - 1][1] && b[i + j - 1] >= b[i + j - 2];
if (i != 0 && j != 0)
{
can_construct[i][j][0] |= can_construct[i - 1][j][1] && a[i + j - 1] >= b[i + j - 2];
can_construct[i][j][1] |= can_construct[i][j - 1][0] && b[i + j - 1] >= a[i + j - 2];
}
}
}
if (!can_construct[n][n][0] && !can_construct[n][n][1])
{
cout << "-1";
return;
}
string ans;
int i = n, j = n, last_pos = (can_construct[n][n][0] ? 0 : 1);
while (i || j)
{
if (i == 0 && j == 1)
{
ans.push_back('B');
break;
}
if (j == 0 && i == 1)
{
ans.push_back('A');
break;
}
if (last_pos == 0)
{
ans.push_back('A');
if (i > 1 && can_construct[i - 1][j][0] && a[i + j - 1] >= a[i + j - 2])
last_pos = 0;
else if (i > 0 && j > 0 && can_construct[i - 1][j][1] && a[i + j - 1] >= b[i + j - 2])
last_pos = 1;
i--;
}
else
{
ans.push_back('B');
if (j > 1 && can_construct[i][j - 1][1] && b[i + j - 1] >= b[i + j - 2])
last_pos = 1;
else if (i > 0 && j > 0 && can_construct[i][j - 1][0] && b[i + j - 1] >= a[i + j - 2])
last_pos = 0;
j--;
}
}
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();
}
