#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<ll> vll;
typedef pair<ll, ll> pll;
const ll maxn = 3e6;
const ll mod = 1e9 + 7;
const ll inf = 2e18;
#define TextIO ifstream fileIn("input.txt"); cin.rdbuf(fileIn.rdbuf()); ofstream fileOut("output.txt"); cout.rdbuf(fileOut.rdbuf());
#define FastIO ios_base::sync_with_stdio(false); cin.tie(NULL);
#define print(x) for (auto i : x) cout << i << ' '; cout << endl
#define out(x) {cout << x << endl; return;}
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define endl '\n'
ll gcd(ll a, ll b) { if (b == 0) return a; return gcd(b, a % b);}
ll lcm(ll a, ll b) { return (a * b) / gcd(a, b); }
ll pw(ll a, ll b, ll md = mod) {ll res = 1; b = max(b, 0ll); while(b) {if (b & 1){res = (a * res) % md;} a = (a * a) % md; b >>= 1;} return (res % md);}
ll n;
ll a[maxn][2];
pll dp[maxn][2];
void solve() {
cin >> n;
for (ll i = 1; i <= 2 * n; i++) cin >> a[i][0];
for (ll i = 1; i <= 2 * n; i++) cin >> a[i][1];
for (ll i = 1; i <= 2 * n; i++) {
for (ll j : {0, 1}) {
dp[i][j] = {n + 1, -1};
for (ll k : {0, 1}) if (a[i - 1][k] <= a[i][j]) {
dp[i][j].first = min(dp[i][j].first, dp[i - 1][k].first + j);
dp[i][j].second = max(dp[i][j].second, dp[i - 1][k].second + j);
}
}
}
ll ok = 0, j = 0;
if (dp[2 * n][0].first <= n && dp[2 * n][0].second >= n) ok = 1;
if (dp[2 * n][1].first <= n && dp[2 * n][1].second >= n) ok = 1, j = 1;
if (!ok) out(-1);
string ans(2 * n, 'A');
ll x = n;
for (ll i = 2 * n; i > 0; i--) {
ans[i - 1] = (j ? 'B' : 'A');
x -= j;
j = (a[i - 1][0] <= a[i][j] && dp[i - 1][0].first <= x && dp[i - 1][0].second >= x ? 0 : 1);
}
cout << ans << endl;
}
int main() {
FastIO
ll t = 1;
// cin >> t;
while (t--)
solve();
return 0;
}
