#include <bits/stdc++.h>
using namespace std;
const int N = 1'000'000 + 10;
int n;
int a[N], b[N];
using pii = pair<int, int>;
pii f[N][2];
pii merge(const pii& i, const pii& j) {
if (i.first == -1) return j;
if (j.first == -1) return i;
return pair(min(i.first, j.first), max(i.second, j.second));
}
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for (int i = 1; i <= 2 * n; ++i) cin >> a[i];
for (int i = 1; i <= 2 * n; ++i) cin >> b[i];
for (int i = 1; i <= 2 * n; ++i) {
{ // f[i][1]
auto& ret = f[i][1];
ret = {-1, -1};
if (b[i - 1] <= a[i]) ret = merge(ret, f[i - 1][0]);
if (a[i - 1] <= a[i]) ret = merge(ret, f[i - 1][1]);
}
{ // f[i][0]
auto& ret = f[i][0];
ret = {-1, -1};
if (b[i - 1] <= b[i]) ret = merge(ret, f[i - 1][0]);
if (a[i - 1] <= b[i]) ret = merge(ret, f[i - 1][1]);
if (ret.first != -1) {
ret.first += 1;
ret.second += 1;
}
}
}
int type = -1;
if (f[2 * n][0].first <= n && n <= f[2 * n][0].second) type = 0;
if (f[2 * n][1].first <= n && n <= f[2 * n][1].second) type = 1;
if (type == -1) {
cout << -1 << "\n";
return 0;
}
int offset = n;
string answer;
for (int i = 2 * n; i >= 1; --i) {
answer += (type ? 'A' : 'B');
offset -= !type;
int cur = (type ? a[i] : b[i]);
type = -1;
if (b[i - 1] <= cur && f[i - 1][0].first <= offset && offset <= f[i - 1][0].second) type = 0;
if (a[i - 1] <= cur && f[i - 1][1].first <= offset && offset <= f[i - 1][1].second) type = 1;
assert(type != -1);
}
reverse(answer.begin(), answer.end());
cout << answer << "\n";
}
