#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define BIT(mask, x) ((mask >> (x)) & 1)
#define FOR(i, a, b) for (int i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for (int i = a, _b = b; i >= _b; --i)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
// -------------------------------------- CON CUA BO HCN --------------------------------------
const int maxn = 4e5 + 3;
int n, a[maxn], b[maxn];
pii dp[maxn][2];
// --------------------------------------------------------------------------------------------
pii merge(const pii &x, const pii &y)
{
return make_pair(min(x.first, y.first), max(x.second, y.second));
}
bool check(const pii &x, int y)
{
return y >= x.first && y <= x.second;
}
void solve()
{
cin >> n;
FOR(i, 1, n << 1) cin >> a[i];
FOR(i, 1, n << 1) cin >> b[i];
FOR(i, 1, n << 1)
{
FOR(j, 0, 1) dp[i][j] = {1e9, -1e9};
if (a[i] > a[i - 1]) dp[i][0] = merge(dp[i][0], make_pair(dp[i - 1][0].first + 1, dp[i - 1][0].second + 1));
if (a[i] > b[i - 1]) dp[i][0] = merge(dp[i][0], make_pair(dp[i - 1][1].first + 1, dp[i - 1][1].second + 1));
if (b[i] > a[i - 1]) dp[i][1] = merge(dp[i][1], dp[i - 1][0]);
if (b[i] > b[i - 1]) dp[i][1] = merge(dp[i][1], dp[i - 1][1]);
}
int type = -1;
if (check(dp[n << 1][0], n)) type = 0;
else if (check(dp[n << 1][1], n)) type = 1;
else return cout << -1, void();
string ans = "";
int u = n;
FORD(i, n << 1, 1)
{
if (type == 0)
{
ans += 'A';
--u;
if (a[i] > b[i - 1] && check(dp[i - 1][1], u)) type = 1;
}
else
{
ans += 'B';
if (b[i] > a[i - 1] && check(dp[i - 1][0], u)) type = 0;
}
}
reverse(all(ans));
cout << ans;
}
signed main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define TASK "TEST"
if (fopen(TASK".INP", "r"))
{
freopen(TASK".INP", "r", stdin);
freopen(TASK".OUT", "w", stdout);
}
solve();
return 0;
}
/* NOTES:
Luon la mot doan lien tiep
*/
