//thuanqvbn03
#include <bits/stdc++.h>
using namespace std;
const int MaxN = 1000005;
int n;
int a[MaxN][2];
bool Color[MaxN][2];
pair<int, int> dp[MaxN][2];
void DFS(int i, int j)
{
if (Color[i][j])
{
return;
}
Color[i][j] = true;
int Min = 1e9, Max = -1e9;
if (a[i][j] <= a[i + 1][0])
{
DFS(i + 1, 0);
Min = min(Min, dp[i + 1][0].first + 1);
Max = max(Max, dp[i + 1][0].second + 1);
}
if (a[i][j] <= a[i + 1][1])
{
DFS(i + 1, 1);
Min = min(Min, dp[i + 1][1].first);
Max = max(Max, dp[i + 1][1].second);
}
dp[i][j] = make_pair(Min, Max);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n;
n *= 2;
for (int j = 0; j < 2; j++)
{
for (int i = 1; i <= n; i++)
{
cin >> a[i][j];
}
}
Color[n][0] = Color[n][1] = 1;
DFS(0, 0);
if (dp[0][0].first > n / 2 || dp[0][0].first > dp[0][0].second)
{
cout << -1;
return 0;
}
int pre = 0, cnt = n / 2;
for (int i = 1; i <= n; i++)
{
if (a[i][0] >= a[i - 1][pre] && cnt - 1 >= dp[i][0].first && cnt - 1 <= dp[i][0].second)
{
cnt--;
cout << 'A';
pre = 0;
}
else
{
cout << 'B';
pre = 1;
}
}
return 0;
}
