#include <bits/stdc++.h>
using namespace std;
#define SZ(x) ((int)(x).size())
typedef long long ll;
const int INF = 1e6;
int main(void)
{
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int n;
cin >> n;
vector<array<int, 2>> cost(2*n);
for (int j(0); j < 2; ++j)
for (int i(0); i < 2*n; ++i)
cin >> cost[i][j];
vector<array<int, 2>> lft(2*n);
vector<array<int, 2> > rght(2*n);
lft[2*n-1][0] = rght[2*n-1][0] = 0;
lft[2*n-1][1] = rght[2*n-1][1] = 1;
for (int i(2*n-2); i >= 0; --i)
{
for (int c(0); c < 2; ++c)
{
lft[i][c] = lft[i][c] = INF;
rght[i][c] = rght[i][c] = -1;
for (int d(0); d < 2; ++d)
if (cost[i][c] <= cost[i+1][d] and lft[i+1][d] != INF)
{
lft[i][c] = min(lft[i][c], c + lft[i+1][d]);
rght[i][c] = max(rght[i][c], c + rght[i+1][d]);
}
}
}
string colors = "AB";
for (int start_col(0); start_col < 2; ++start_col)
{
if (lft[0][start_col] <= n and rght[0][start_col] >= n)
{
int cur_col = start_col;
int want = n - start_col;
for (int i(0); i < 2*n-1; ++i)
{
cout << colors[cur_col];
for (int nxt_col(0); nxt_col < 2; ++nxt_col)
if (cost[i][cur_col] <= cost[i+1][nxt_col]
and lft[i+1][nxt_col] <= want
and rght[i+1][nxt_col] >= want)
{
cur_col = nxt_col;
want -= cur_col;
break;
}
}
cout << colors[cur_col] << endl;
return 0;
}
}
cout << -1 << endl;
}
