#include <bits/stdc++.h>
#define debug(x) cerr << #x << " = " << x << ", ";
#define ll long long
#define pb push_back
using namespace std;
#define FAST_IO \
ios_base::sync_with_stdio(false); \
cin.tie(NULL); \
cout.tie(NULL);
int main()
{
FAST_IO
ll n, len;
cin >> n;
len = 2 * n;
vector<vector<ll>> v(len, vector<ll>(2));
for (int i = 0; i < len; i++)
{
cin >> v[i][1];
}
for (int i = 0; i < len; i++)
{
cin >> v[i][0];
}
vector<vector<pair<pair<ll, ll>, ll>>> dp(len, vector<pair<pair<ll, ll>, ll>>(2));
for (int i = 0; i < len; i++)
{
dp[i][0] = {{-1, -1}, -1};
dp[i][1] = {{-1, -1}, -1};
}
dp[0][0] = {{0, 0}, -1};
dp[0][1] = {{1, 1}, -1};
for (int i = 0; i < len - 1; i++)
{
for (int prev = 0; prev < 2; prev++)
{
if (dp[i][prev].first != make_pair((ll)-1, (ll)-1))
{
for (int nxt = 0; nxt < 2; nxt++)
{
pair<ll, ll> pp;
if (v[i][prev] > v[i + 1][nxt])
{
continue;
}
pp = {dp[i][prev].first.first + nxt, dp[i][prev].first.second + nxt};
if (dp[i + 1][nxt].first == make_pair((ll)-1, (ll)-1))
{
dp[i + 1][nxt].first = pp;
dp[i + 1][nxt].second = prev;
}
else
{
dp[i + 1][nxt].first = {min(dp[i + 1][nxt].first.first, pp.first), max(dp[i + 1][nxt].first.second, pp.second)};
if (dp[i + 1][nxt].second == 0)
{
if (prev == 1)
{
dp[i + 1][nxt].second = 2;
}
}
else if (dp[i + 1][nxt].second == 1)
{
if (prev == 0)
dp[i + 1][nxt].second = 2;
}
}
}
}
}
}
ll cnt = n;
string ans = "";
// debug(dp[len - 1][0].first.first);
// debug(dp[len - 1][0].first.second);
// debug(dp[len - 1][1].first.first);
// debug(dp[len - 1][1].first.second);
// cout << endl;
if (!((dp[len - 1][0].first.first <= n && dp[len - 1][0].first.second >= n) || (dp[len - 1][1].first.first <= n && dp[len - 1][1].first.second >= n)))
{
cout << -1 << endl;
return 0;
}
bool from2 = false;
for (int i = len - 1; i >= 0; i--)
{
for (int nxt = 0; nxt < 2; nxt++)
{
pair<ll, ll> curr = dp[i][nxt].first;
int prevv = dp[i][nxt].second;
// debug(i);
// debug(prevv);
// debug(curr.first);
// debug(curr.second);
// debug(cnt);
// debug(nxt);
// cout << endl;
// cout << "==========" << endl;
if (from2 && !(cnt >= curr.first && cnt <= curr.second))
{
from2 = false;
nxt = -1;
continue;
}
if (cnt >= curr.first && cnt <= curr.second)
{
ans += (nxt == 0 ? "B" : "A");
cnt -= (nxt == 0 ? 0 : 1);
if (prevv == 2)
{
if (cnt)
{
from2 = true;
i--;
nxt = 0;
continue;
}
else
{
i--;
nxt = -1;
continue;
}
}
if (prevv == 1)
{
i--;
nxt = 0;
continue;
}
if (prevv == 0)
{
i--;
nxt = -1;
continue;
}
break;
}
}
}
// cout << cnt << endl;
reverse(ans.begin(), ans.end());
// cout << ans.size() << endl;
cout << ans << endl;
return 0;
}
