#include <bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(0);cin.tie(0);
#define s second
#define f first
typedef long long ll;
const ll MOD = 1e9 + 7;
const ll LOGN = 22;
const ll MAXN = 1e6 + 5;
int A[MAXN], B[MAXN];
int dp[MAXN][2][2];
vector<char> ans;
int main() {
fast
int N;
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 = 0; i < MAXN; i++) {
dp[i][0][0] = 2*N+2, dp[i][0][1] = 0;
dp[i][1][0] = 2*N+2, dp[i][1][1] = 0;
}
dp[0][0][0] = dp[0][0][1] = dp[0][1][0] = dp[0][1][1] = 0;
for (int i = 1; i <= 2*N; i++) {
if (A[i-1] <= A[i]) {
dp[i][0][0] = min(dp[i][0][0], dp[i-1][0][0] + 1);
dp[i][0][1] = max(dp[i][0][1], dp[i-1][0][1] + 1);
}
if (A[i-1] <= B[i]) {
dp[i][1][0] = min(dp[i][1][0], dp[i-1][0][0]);
dp[i][1][1] = max(dp[i][1][1], dp[i-1][0][1]);
}
if (B[i-1] <= A[i]) {
dp[i][0][0] = min(dp[i][0][0], dp[i-1][1][0] + 1);
dp[i][0][1] = max(dp[i][0][1], dp[i-1][1][1] + 1);
}
if (B[i-1] <= B[i]) {
dp[i][1][0] = min(dp[i][1][0], dp[i-1][1][0]);
dp[i][1][1] = max(dp[i][1][1], dp[i-1][1][1]);
}
}
int last = -1;
if (dp[2*N][0][0] <= N && N <= dp[2*N][0][1])
last = 0;
else if (dp[2*N][1][0] <= N && N <= dp[2*N][1][1])
last = 1;
if (last == -1) {
cout << "-1\n";
return 0;
}
if (last == 0)
ans.push_back('A');
else
ans.push_back('B');
int now = N - (last == 0);
for (int i = 2*N - 1; i >= 1; i--) {
if (dp[i][0][0] <= now && now <= dp[i][0][1] && A[i] <= (last == 0 ? A[i+1] : B[i+1]))
last = 0;
else if (dp[i][1][0] <= now && now <= dp[i][1][1])
last = 1;
now = now - (last == 0);
if (last == 0)
ans.push_back('A');
else
ans.push_back('B');
}
for (int i = ans.size() - 1; i >= 0; i--)
cout << ans[i];
cout << "\n";
}
