#include <bits/stdc++.h>
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
using namespace std;
#define int long long
#define ll long long
#define vi vector<long long>
#define pb push_back
#define sz(s) (int)s.size()
#define all(v) v.begin(), v.end()
#define show(a) cerr << #a <<" -> "<< a <<"\n"
#define pp pair<int,int>
#define FF first
#define SS second
#define endl "\n"
#define ld long double
const int N = 1e6 + 2, N3 = 1e3 + 6, inf = 1e18 + 7, LOG = 20;
map<char, int> md{{'N', 0}, {'E', 1}, {'S', 2}, {'W', 3}};
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
string stepDir = "RDLU";
int n, a[N], b[N], dp[4001][2001], col[4001][2001];
main () {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// freopen(".in", "r", stdin);
// freopen(".out", "w", stdout);
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 = 0; i <= n * 2; i++) {
for (int j = 0; j <= n; j++) {
dp[i][j] = inf;
}
}
dp[0][0] = 0;
for (int i = 1; i <= n * 2; i++) {
for (int j = 0; j <= min(i, n); j++) {
if (j != 0 && a[i] >= dp[i - 1][j - 1]) {
dp[i][j] = a[i];
col[i][j] = 1;
}
if (b[i] >= dp[i - 1][j] && b[i] < dp[i][j]) {
dp[i][j] = b[i];
col[i][j] = 2;
}
}
}
vi v;
int i = n * 2, j = n;
while (i > 0) {
if (dp[i][j] == inf) {
cout << -1;
return 0;
}
v.pb(col[i][j]);
if (col[i][j] == 1) {
j--;
}
i--;
}
reverse(all(v));
for (auto to : v) {
if (to == 1) cout << "A";
else cout << "B";
}
return 0;
}
