#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 5e5 + 2;
bool can[2][2 * N], prv[2][2 * N];
int a[2][2 * N];
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n; cin >> n;
for (int j = 0; j < 2; j++) for (int i = 1; i <= 2 * n; i++) cin >> a[j][i];
a[0][2 * n + 1] = 1e9;
can[0][1] = can[1][1] = 1;
for (int i = 2; i <= 2 * n + 1; i++) {
bool manji = 0, veci = 1;
if (a[0][i - 1] > a[1][i - 1]) swap(manji, veci);
for (int j = 0; j < 2; j++) {
if (a[veci][i - 1] <= a[j][i] && can[veci][i - 1]) {
can[j][i] = 1;
prv[j][i] = veci;
}
else if (a[manji][i - 1] <= a[j][i] && can[manji][i - 1]) {
can[j][i] = 1;
prv[j][i] = manji;
}
}
}
if (can[0][2 * n + 1] == 0) {
cout << -1 << en;
return 0;
}
int i = 2 * n + 1, j = 0;
vector<int> ans;
int diff = 0;
while (1) {
j = prv[j][i];
i -= 1;
if (i == 0) break;
diff += 2 * j - 1;
ans.push_back(j);
}
ans.push_back(-1);
reverse(ans.begin(), ans.end());
for (int z = 0; z < 3000; z++) {
for (int i = 2 * n; i >= 1; i--) {
if (ans[i] == 0 && diff < 0 && can[1][i] == 1) {
bool moze = 1;
if (i >= 2 && a[ans[i - 1]][i - 1] > a[1][i]) moze = 0;
if (i < 2 * n && a[1][i] > a[ans[i + 1]][i + 1]) moze = 0;
if (moze) {
diff += 2;
ans[i] ^= 1;
}
}
else if (ans[i] == 1 && diff > 0 && can[0][i] == 1) {
bool moze = 1;
if (i >= 2 && a[ans[i - 1]][i - 1] > a[0][i]) moze = 0;
if (i < 2 * n && a[0][i] > a[ans[i + 1]][i + 1]) moze = 0;
if (moze) {
diff -= 2;
ans[i] ^= 1;
}
}
}
}
if (diff != 0) {
cout << -1 << en;
return 0;
}
for (int i = 1; i <= 2 * n; i++) {
if (ans[i] == 0) cout << 'A';
if (ans[i] == 1) cout << 'B';
}
return 0;
}
