#include <bits/extc++.h>
using namespace __gnu_pbds;
using namespace std;
#define int long long
#define ll long long
// #define double long double
#define all(x) x.begin(), x.end()
#define debug(x) do{auto _x = x; cerr << #x << " = " << _x << endl;} while(0)
#define f first
#define s second
using pii = pair<int, int>;
// #define endl '\n'
const ll inf = 1ll << 60;
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n; cin >> n; n *= 2;
vector<int> a(n), b(n);
for(int i = 0; i < n; i++) {
cin >> a[i];
}
for(int i = 0; i < n; i++) {
cin >> b[i];
}
vector<pair<pii, pii>> dp(n, {{-1, -1}, {-1, -1}});
dp[n - 1] = {{1, 1}, {0, 0}};
auto merge = [&](pii a, pii b) {
if(min(a, b) == pii{-1, -1}) return max(a, b);
return pii{min(a.f, b.f), max(a.s, b.s)};
};
for(int i = n - 2; i >= 0; i--) {
if(a[i] <= a[i + 1]) {
dp[i].f = merge(dp[i].f, dp[i + 1].f);
}
if(a[i] <= b[i + 1]) {
dp[i].f = merge(dp[i].f, dp[i + 1].s);
}
if(dp[i].f != pii{-1, -1}) {
dp[i].f.f++;
dp[i].f.s++;
}
if(b[i] <= a[i + 1]) {
dp[i].s = merge(dp[i].s, dp[i + 1].f);
}
if(b[i] <= b[i + 1]) {
dp[i].s = merge(dp[i].s, dp[i + 1].s);
}
// cout << i << " " << dp[i].f.f << " " << dp[i].f.s << " " << dp[i].s.f << " " << dp[i].s.s << endl;
}
int rem = n / 2;
int last = -1;
string ans;
auto die = [&]() {
cout << -1 << endl;
exit(0);
};
for(int i = 0; i < n; i++) {
if(last <= a[i] && dp[i].f.f <= rem && rem <= dp[i].f.s) {
ans += "A";
last = a[i];
rem--;
} else if(last <= b[i] && dp[i].s != pii{-1, -1}) {
ans += "B";
last = b[i];
} else {
die();
}
}
if(count(all(ans), 'A') != n / 2) die();
cout << ans << endl;
}
