/*
Ben Watson
Quang Minh MasterDDDDD
*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
const string name = "test";
void solve();
signed main()
{
if (fopen((name + ".inp").c_str(), "r"))
{
freopen((name + ".inp").c_str(), "r", stdin);
freopen((name + ".out").c_str(), "w", stdout);
}
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
solve();
return 0;
}
// main program
const int maxn = 1e6 + 1;
pair<int, int> dp[2][maxn];
int a[maxn], b[maxn];
int n;
void transit(pair<int, int> s, pair<int, int>& t, int offset)
{
int l = s.first, r = s.second, u = t.first, v = t.second;
if (l == -1)
return;
l += offset; r += offset;
r = min(r, n);
if (u == -1)
t = {l, r};
else
t = {min(l, u), max(r, v)};
}
bool include(pair<int, int> p, int x) { return (p.first <= x && x <= p.second); }
void solve()
{
cin >> n;
for (int i = 1; i <= 2 * n; i++)
cin >> a[i];
for (int i = 1; i <= 2 * n; i++)
cin >> b[i];
dp[0][0] = dp[1][0] = {0, 0};
for (int i = 1; i <= 2 * n; i++)
{
// use A
dp[0][i] = {-1, -1};
if (a[i - 1] <= a[i])
transit(dp[0][i - 1], dp[0][i], 1);
if (b[i - 1] <= a[i])
transit(dp[1][i - 1], dp[0][i], 1);
// use B
dp[1][i] = {-1, -1};
if (a[i - 1] <= b[i])
transit(dp[0][i - 1], dp[1][i], 0);
if (b[i - 1] <= b[i])
transit(dp[1][i - 1], dp[1][i], 0);
}
int st = -1;
if (include(dp[0][2 * n], n)) st = 0;
if (include(dp[1][2 * n], n)) st = 1;
if (st == -1)
{
cout << -1 << '\n';
return;
}
int cur = n;
vector<char> ans(2 * n + 1);
for (int i = 2 * n; i > 0; i--)
{
ans[i] = (st == 0 ? 'A' : 'B');
int x = (st == 0 ? a[i] : b[i]);
if (st == 0)
cur--;
if (a[i - 1] <= x && include(dp[0][i - 1], cur))
st = 0;
if (b[i - 1] <= x && include(dp[1][i - 1], cur))
st = 1;
}
for (int i = 1; i <= 2 * n; i++)
cout << ans[i];
cout << '\n';
}
