#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
vector<vector<ll>> g;
vector<ll> vis, p;
map<array<ll, 3>, ll> cv;
void dfs(ll u, ll c1, ll c2) {
p.push_back(u);
c1 += (u < g.size() / 2);
c2 += (u >= g.size() / 2);
if (cv.find({u, c1, c2}) != cv.end()) return;
cv[{u, c1, c2}] = 1;
if (c1 == g.size() / 4 && c2 == g.size() / 4) {
for (ll i = 0; i < p.size(); i++) {
if (p[i] < g.size() / 2) cout << 'A';
else cout << 'B';
}
exit(0);
}
for (ll v : g[u]) {
if (!vis[v]) {
dfs(v, c1, c2);
}
}
p.pop_back();
}
void solve() {
ll n;
cin >> n;
n *= 2;
vector<ll> a(n), b(n);
for (ll& x : a) cin >> x;
for (ll& x : b) cin >> x;
g.resize(n + n);
vis.resize(n + n);
for (ll i = 0; i < n - 1; i++) {
if (a[i] <= a[i + 1]) g[i].push_back(i + 1);
if (a[i] <= b[i + 1]) g[i].push_back(i + 1 + n);
if (b[i] <= a[i + 1]) g[i + n].push_back(i + 1);
if (b[i] <= b[i + 1]) g[i + n].push_back(i + n + 1);
}
dfs(0, 0, 0);
vis.assign(n + n, 0);
cv.clear();
dfs(n, 0, 0);
cout << -1;
}
signed main() {
cin.tie(nullptr);
ios_base::sync_with_stdio(false);
ll t = 1;
//cin >> t;
while (t--) {
solve();
}
return 0;
}
