/**
____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|
**/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N_MAX = 1000000;
const int A = 0;
const int B = 1;
int n;
int a[N_MAX + 2];
int b[N_MAX + 2];
int L[N_MAX + 2][2];
int R[N_MAX + 2][2];
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n;
n *= 2;
for(int i = 1; i <= n; i++)
cin >> a[i];
for(int i = 1; i <= n; i++)
cin >> b[i];
for(int i = 1; i <= n; i++)
{
L[i][A] = L[i][B] = INT_MAX / 2;
R[i][A] = R[i][B] = INT_MIN / 2;
}
L[1][A] = 1;
R[1][A] = 1;
L[1][B] = 0;
R[1][B] = 0;
for(int i = 1; i < n; i++)
{
if(a[i] <= a[i + 1])
{
L[i + 1][A] = min(L[i + 1][A], L[i][A] + 1);
R[i + 1][A] = max(R[i + 1][A], R[i][A] + 1);
}
if(a[i] <= b[i + 1])
{
L[i + 1][B] = min(L[i + 1][B], L[i][A]);
R[i + 1][B] = max(R[i + 1][B], R[i][A]);
}
if(b[i] <= a[i + 1])
{
L[i + 1][A] = min(L[i + 1][A], L[i][B] + 1);
R[i + 1][A] = max(R[i + 1][A], R[i][B] + 1);
}
if(b[i] <= b[i + 1])
{
L[i + 1][B] = min(L[i + 1][B], L[i][B]);
R[i + 1][B] = max(R[i + 1][B], R[i][B]);
}
}
bool okA = (L[n][A] <= n / 2 && n / 2 <= R[n][A]);
bool okB = (L[n][B] <= n / 2 && n / 2 <= R[n][B]);
if(okA == false && okB == false)
{
cout << "-1\n";
return 0;
}
int pos = n;
int cnt = n / 2;
int last = (okA == true ? A : B);
string sol;
while(pos >= 2)
{
if(last == A)
sol += 'A';
else
sol += 'B';
if(last == A)
{
if(a[pos - 1] <= a[pos] && L[pos - 1][A] + 1 <= cnt && cnt <= R[pos - 1][A] + 1)
last = A;
else if(b[pos - 1] <= a[pos] && L[pos - 1][B] + 1 <= cnt && cnt <= R[pos - 1][B] + 1)
last = B;
cnt--;
}
else
{
if(a[pos - 1] <= b[pos] && L[pos - 1][A] <= cnt && cnt <= R[pos - 1][A])
last = A;
else if(b[pos - 1] <= b[pos] && L[pos - 1][B] <= cnt && cnt <= R[pos - 1][B])
last = B;
}
pos--;
}
if(last == A)
sol += 'A';
else
sol += 'B';
reverse(sol.begin(), sol.end());
cout << sol << "\n";
return 0;
}
