#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define endl '\n'
using namespace std;
const int maxn = 5e5 + 3;
const int inf = 1e9;
int n, a[maxn * 2], b[maxn * 2];
void read()
{
cin >> n;
for (int i = 1; i <= n * 2; i++)
cin >> a[i];
for (int i = 1; i <= n * 2; i++)
cin >> b[i];
}
pair <int, int> dp[maxn * 2][2];
void solve()
{
dp[1][0] ={1, 1};
dp[1][1] = {0, 0};
for (int i = 2; i <= n * 2; i++)
{
dp[i][0] = dp[i][1] = {inf, -inf};
if (a[i] >= a[i-1] && dp[i-1][0].first <= dp[i-1][0].second)
{
dp[i][0].first = min(dp[i][0].first, dp[i-1][0].first + 1);
dp[i][0].second = max(dp[i][0].second, dp[i-1][0].second + 1);
}
if (a[i] >= b[i-1] && dp[i-1][1].first <= dp[i-1][1].second)
{
dp[i][0].first = min(dp[i][0].first, dp[i-1][1].first + 1);
dp[i][0].second = max(dp[i][0].second, dp[i-1][1].second + 1);
}
if (b[i] >= a[i-1] && dp[i-1][0].first <= dp[i-1][0].second)
{
dp[i][1].first = min(dp[i][1].first, dp[i-1][0].first);
dp[i][1].second = max(dp[i][1].second, dp[i-1][0].second);
}
if (b[i] >= b[i-1] && dp[i-1][1].first <= dp[i-1][1].second)
{
dp[i][1].first = min(dp[i][1].first, dp[i-1][1].first);
dp[i][1].second = max(dp[i][1].second, dp[i-1][1].second);
}
}
int last = -1, left = n;
vector <char> ans;
if (dp[2 * n][0].first <= n && dp[2 * n][0].second >= n)
{
ans.push_back('A');
last = a[2 * n];
left--;
}
else
if (dp[2 * n][1].first <= n && dp[2 * n][1].second >= n)
{
ans.push_back('B');
last = b[2 * n];
}
if (last == -1)
{
cout << -1 << endl;
return;
}
for (int i = 2 * n - 1; i >= 1; i--)
{
if (a[i] <= last && dp[i][0].first <= left && dp[i][0].second >= left)
{
last = a[i];
left--;
ans.push_back('A');
}
else
{
last = b[i];
ans.push_back('B');
}
}
reverse(ans.begin(), ans.end());
for (auto i: ans)
cout << i;
cout << endl;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
read();
solve();
}
