#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
const int DIM = 1000005;
pair<int, int> seg[2][DIM];
char ans[DIM];
int arr[2][DIM];
void solve(int k, int n, int rem) {
if (n == 0)
cout << (ans + 1);
else {
if (k == 0)
ans[n] = 'A';
else
ans[n] = 'B';
if (arr[0][n - 1] <= arr[k][n] and seg[0][n - 1].first != -1 and
seg[0][n - 1].first <= rem - (1 - k) and rem - (1 - k) <= seg[0][n - 1].second)
solve(0, n - 1, rem - (1 - k));
else
solve(1, n - 1, rem - (1 - k));
}
}
void update(pair<int, int> &s1, pair<int, int> &s2) {
if (s2.first == -1)
return;
if (s1.first == -1)
s1 = s2;
else
s1 = make_pair(min(s1.first, s2.first), max(s1.second, s2.second));
}
int main(void) {
// freopen("building4.in", "r", stdin);
// freopen("building4.out", "w", stdout);
int n;
cin >> n;
for (int k = 0; k <= 1; ++k) {
for (int i = 1; i <= n * 2; ++i) {
cin >> arr[k][i];
seg[k][i] = {-1, -1};
}
}
seg[0][0] = {0, 0};
for (int i = 1; i <= n * 2; ++i) {
for (int k1 = 0; k1 <= 1; ++k1)
for (int k2 = 0; k2 <= 1; ++k2)
if (arr[k1][i - 1] <= arr[k2][i])
update(seg[k2][i], seg[k1][i - 1]);
if (seg[0][i].first != -1)
++seg[0][i].first, ++seg[0][i].second;
}
/* for (int i = 0; i <= n * 2; ++i) {
for (int k = 0; k <= 1; ++k)
cout << seg[k][i].first << " " << seg[k][i].second << " ";
cout << endl;
} */
if (seg[0][n * 2].first != -1 and seg[0][n * 2].first <= n and seg[0][n * 2].second >= n)
solve(0, n * 2, n);
else if (seg[1][n * 2].first != -1 and seg[1][n * 2].first <= n and seg[1][n * 2].second >= n)
solve(1, n * 2, n);
else
cout << -1 << "\n";
return 0;
}
