#include <bits/stdc++.h>
using namespace std;
void setup()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
int n, a[1000001][2], lb[1000001][2], rb[1000001][2];
inline void Print(int ind, int cur, int num)
{
if (ind == 0)
{
return;
}
for (int i = 1; i >= 0; --i)
{
if (a[ind - 1][i] <= a[ind][cur] &&
lb[ind - 1][i] <= num && num <= rb[ind - 1][i])
{
Print(ind - 1, i, num - i);
break;
}
}
cout << char('A' + cur);
}
int main()
{
setup();
cin >> n;
for (int j = 0; j < 2; ++j)
{
for (int i = 1; i <= 2 * n; ++i)
{
cin >> a[i][j];
}
}
for (int i = 1; i <= 2 * n; ++i)
{
for (int j = 0; j < 2; ++j)
{
lb[i][j] = 1e9;
rb[i][j] = -1e9;
for (int k = 0; k < 2; ++k)
{
if (a[i - 1][k] <= a[i][j])
{
lb[i][j] = min(lb[i][j], lb[i - 1][k] + j);
rb[i][j] = max(rb[i][j], rb[i - 1][k] + j);
}
}
}
}
for (int i = 0; i < 2; ++i)
{
if (lb[2 * n][i] <= n && n <= rb[2 * n][i])
{
Print(2 * n, i, n);
return 0;
}
}
cout << -1;
return 0;
}
