#include <bits/stdc++.h>
using namespace std;
template<class T, class U>
void ckmin(T &a, U b)
{
if (a > b) a = b;
}
template<class T, class U>
void ckmax(T &a, U b)
{
if (a < b) a = b;
}
#define MP make_pair
#define PB push_back
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define SZ(x) ((int) (x).size())
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, a, b) for (auto i = (a); i < (b); i++)
#define FORD(i, a, b) for (auto i = (a) - 1; i >= (b); i--)
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
const int INF = 1000000007;
const int MAXN = 1000013;
int N;
pii arr[MAXN];
pair<pii, pii> dp[MAXN];
bitset<MAXN> ans;
int32_t main()
{
cout << fixed << setprecision(12);
cerr << fixed << setprecision(4);
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> N;
FOR(i, 0, 2 * N)
{
cin >> arr[i].fi;
}
FOR(i, 0, 2 * N)
{
cin >> arr[i].se;
}
dp[0] = {{0, 0}, {0, 0}};
FOR(i, 0, 2 * N)
{
dp[i + 1] = {{INF, -INF}, {INF, -INF}};
if (i == 0 || arr[i - 1].fi <= arr[i].fi)
{
ckmin(dp[i + 1].fi.fi, dp[i].fi.fi);
ckmax(dp[i + 1].fi.se, dp[i].fi.se);
}
if (i == 0 || arr[i - 1].se <= arr[i].fi)
{
ckmin(dp[i + 1].fi.fi, dp[i].se.fi);
ckmax(dp[i + 1].fi.se, dp[i].se.se);
}
if (i == 0 || arr[i - 1].fi <= arr[i].se)
{
ckmin(dp[i + 1].se.fi, dp[i].fi.fi + 1);
ckmax(dp[i + 1].se.se, dp[i].fi.se + 1);
}
if (i == 0 || arr[i - 1].se <= arr[i].se)
{
ckmin(dp[i + 1].se.fi, dp[i].se.fi + 1);
ckmax(dp[i + 1].se.se, dp[i].se.se + 1);
}
}
if ((dp[2 * N].fi.se < N || dp[2 * N].fi.fi > N) && (dp[2 * N].se.se < N || dp[2 * N].se.fi > N))
{
cout << "-1\n";
return 0;
}
int rem = N;
bool dir = (dp[2 * N].se.fi <= N && N <= dp[2 * N].se.se);
FORD(i, 2 * N, 0)
{
if (dir)
{
ans[i] = true;
rem--;
if (dp[i].fi.fi <= rem && rem <= dp[i].fi.se && (i == 0 || arr[i - 1].fi <= arr[i].se))
{
dir = false;
}
else
{
dir = true;
}
}
else
{
ans[i] = false;
if (dp[i].fi.fi <= rem && rem <= dp[i].fi.se && (i == 0 || arr[i - 1].fi <= arr[i].fi))
{
dir = false;
}
else
{
dir = true;
}
}
}
FOR(i, 0, 2 * N)
{
cout << (ans[i] ? 'B' : 'A');
}
cout << '\n';
return 0;
}
