#include <bits/stdc++.h>
#define dbg() cerr <<
#define name(x) (#x) << ": " << (x) << ' ' <<
using namespace std;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n; cin >> n;
vector<int> a(2 * n);
for (int &x : a) cin >> x;
vector<int> b(2 * n);
for (int &x : b) cin >> x;
// daca setam i pe A / B exista un interval compact de valori j
// care sa reprezinte nr de alegeri B facute care sa respecte conditia
// -> calculam minimul si maximul
vector<vector<int>> min_dp(2 * n, vector<int>(2, -1));
vector<vector<int>> max_dp(2 * n, vector<int>(2, -1));
auto UpdateMin = [&](int i, int si, int j, int sj) {
if (min_dp[j][sj] == -1) return;
if (min_dp[i][si] == -1 || min_dp[i][si] > min_dp[j][sj] + (si == 1)) {
min_dp[i][si] = min_dp[j][sj] + (si == 1);
}
};
auto UpdateMax = [&](int i, int si, int j, int sj) {
if (max_dp[j][sj] == -1) return;
if (max_dp[i][si] == -1 || max_dp[i][si] < max_dp[j][sj] + (si == 1)) {
max_dp[i][si] = max_dp[j][sj] + (si == 1);
}
};
min_dp[0][0] = 0;
max_dp[0][0] = 0;
min_dp[0][1] = 1;
max_dp[0][1] = 1;
for (int i = 1; i < 2 * n; ++i) {
// punem a daca se poate
if (a[i] >= a[i - 1]) {
UpdateMin(i, 0, i - 1, 0);
UpdateMax(i, 0, i - 1, 0);
}
if (a[i] >= b[i - 1]) {
UpdateMin(i, 0, i - 1, 1);
UpdateMax(i, 0, i - 1, 1);
}
// dbg() name(i) name(min_dp[i][0]) name(max_dp[i][0]) endl;
// punem b
if (b[i] >= a[i - 1]) {
UpdateMin(i, 1, i - 1, 0);
UpdateMax(i, 1, i - 1, 0);
}
if (b[i] >= b[i - 1]) {
UpdateMin(i, 1, i - 1, 1);
UpdateMax(i, 1, i - 1, 1);
}
// dbg() name(i) name(min_dp[i][1]) name(max_dp[i][1]) endl;
}
auto Check = [&](int i, int si, int cnt) {
return min_dp[i][si] <= cnt && cnt <= max_dp[i][si];
};
int lst = -1;
if (Check(2 * n - 1, 0, n)) lst = 0;
if (Check(2 * n - 1, 1, n)) lst = 1;
if (lst == -1) {
cout << "-1\n";
return 0;
}
string ans;
int cnt = n;
for (int i = 2 * n - 1; i >= 0; --i) {
ans += lst == 0 ? 'A' : 'B';
cnt -= lst == 1;
int curr = lst == 0 ? a[i] : b[i];
if (i == 0) break;
bool ok = false;
if (curr >= a[i - 1] && Check(i - 1, 0, cnt)) {
lst = 0;
ok = true;
}
if (curr >= b[i - 1] && Check(i - 1, 1, cnt)) {
lst = 1;
ok = true;
}
assert(ok);
}
assert(cnt == 0);
reverse(ans.begin(), ans.end());
cout << ans << endl;
// vector<vector<vector<int>>> from(2 * n,
// vector<vector<int>>(n + 1,
// vector<int>(2, -1)));
//
// // dp[i][cate_b][a / b]
// from[0][0][0] = 1;
// from[0][1][1] = 1;
// for (int i = 1; i < 2 * n; ++i) {
// for (int j = 0; j <= n; ++j) {
// // punem din a
// if (a[i] >= a[i - 1] && from[i - 1][j][0] != -1)
// from[i][j][0] = 0;
// if (a[i] >= b[i - 1] && from[i - 1][j][1] != -1)
// from[i][j][0] = 1;
//
//// if (from[i][j][0] != -1) dbg() name(i) name(j) 0 << name(from[i][j][0]) endl;
//// if (from[i][j][0] != -1) {
//// dbg() name(i) name(j) endl;
//// }
//
// if (j == 0) continue;
// if (b[i] >= a[i - 1] && from[i - 1][j - 1][0] != -1)
// from[i][j][1] = 0;
// if (b[i] >= b[i - 1] && from[i - 1][j - 1][1] != -1)
// from[i][j][1] = 1;
//// if (from[i][j][1] != -1) dbg() name(i) name(j) 1 << name(from[i][j][1]) endl;
// if (from[i][j][1] != -1) {
// dbg() name(i) name(j) endl;
// }
// }
// }
// int lst = -1;
// if (from[2 * n - 1][n][0] != -1) lst = 0;
// if (from[2 * n - 1][n][1] != -1) lst = 1;
//
// if (lst == -1) {
// cout << "-1\n";
// return 0;
// }
//
// string ans;
// int cnt = n;
// for (int i = 2 * n - 1; i >= 0; --i) {
// ans += lst == 0 ? 'A' : 'B';
// int curr = lst;
// lst = from[i][cnt][lst];
// cnt -= curr == 1;
// }
// reverse(ans.begin(), ans.end());
// cout << ans << endl;
}
