#include <bits/stdc++.h>
#define int long long
#define MAX 600000
using namespace std;
typedef array<int, 2> pr;
int A[MAX], B[MAX];
pr dp[MAX][2];
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
int N, K, Z;
bool X, Y;
string res;
cin >> N;
for (int i = 1; i <= N * 2; i++)
cin >> A[i];
for (int i = 1; i <= N * 2; i++)
cin >> B[i];
for (int i = 1; i <= N * 2; i++) {
X = A[i] >= A[i - 1] && dp[i - 1][0][0] != -1;
Y = A[i] >= B[i - 1] && dp[i - 1][1][0] != -1;
if (X && Y)
dp[i][0] = {min(dp[i - 1][0][0], dp[i - 1][1][0]), max(dp[i - 1][0][1], dp[i - 1][1][1])};
else if (X)
dp[i][0] = dp[i - 1][0];
else if (Y)
dp[i][0] = dp[i - 1][1];
else
dp[i][0] = {-1, -1};
X = B[i] >= A[i - 1] && dp[i - 1][0][0] != -1;
Y = B[i] >= B[i - 1] && dp[i - 1][1][0] != -1;
if (X && Y)
dp[i][1] = {min(dp[i - 1][0][0], dp[i - 1][1][0]) + 1, max(dp[i - 1][0][1], dp[i - 1][1][1]) + 1};
else if (X)
dp[i][1] = {dp[i - 1][0][0] + 1, dp[i - 1][0][1] + 1};
else if (Y)
dp[i][1] = {dp[i - 1][1][0] + 1, dp[i - 1][1][1] + 1};
else
dp[i][1] = {-1, -1};
}
if (!(dp[N * 2][0][0] <= N && N <= dp[N * 2][0][1]) && !(dp[N * 2][1][0] <= N && N <= dp[N * 2][1][1])) {
cout << -1 << '\n';
return 0;
}
K = N;
for (int i = N * 2; i >= 1; i--) {
if ((i == N * 2 || Z >= A[i]) && dp[i][0][0] != -1 && dp[i][0][0] <= K && K <= dp[i][0][1])
res.push_back('A'), Z = A[i];
else
res.push_back('B'), K--, Z = B[i];
}
reverse(res.begin(), res.end());
cout << res << '\n';
return 0;
}
