#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define lsb(x) (x & (-x))
using namespace std;
const int MAXN = (int)1e6;
int arr[2 * MAXN + 1];
pair<int, int> dp[2 * MAXN + 1];
int main() {
#ifdef HOME
ifstream cin("C.in");
ofstream cout("C.out");
#endif
int i, j, n;
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
cin >> n;
n *= 2;
for(i = 1; i <= n; i++) {
cin >> arr[2 * i - 1];
}
for(i = 1; i <= n; i++) {
cin >> arr[2 * i];
}
for(i = 1; i <= 2 * n; i++) {
dp[i].first = 2 * n;
dp[i].second = -2 * n;
int cur = 1;
if(i % 2 == 0) {
cur = -1;
}
for(j = i - 1; j >= max(0, i - 3); j--) {
if((i + 1) / 2 - (j + 1) / 2 == 1 && arr[j] <= arr[i]) {
dp[i].first = min(dp[i].first, dp[j].first + cur);
dp[i].second = max(dp[i].second, dp[j].second + cur);
}
}
//cerr << arr[i] << " " << dp[i].first << " " << dp[i].second << "\n";
}
string str;
int pos = 2 * n;
if(dp[2 * n - 1].first <= 0 && dp[2 * n - 1].second >= 0) {
pos = 2 * n - 1;
}
if(dp[pos].first > 0 || dp[pos].second < 0) {
cout << -1;
return 0;
}
int val = 0;
while(pos != 0) {
int cur = 1;
if(pos & 1) {
str += 'A';
}
else {
str += 'B';
cur = -1;
}
//cerr << pos << "\n";
for(j = pos - 1; j >= max(0, pos - 3); j--) {
if(arr[pos] >= arr[j] && (pos + 1) / 2 - (j + 1) / 2 == 1 && dp[j].first + cur <= val && dp[j].second + cur >= val) {
pos = j, val -= cur;
break;
}
}
}
reverse(str.begin(), str.end());
cout << str;
return 0;
}
