// Starcraft 2 enjoyer //
#include <bits/stdc++.h>
// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
#define LSOne(X) ((X) & -(X))
const int N = 1e6 + 5;
const int K = 1e2 + 5;
const int M = 2e5 + 5;
const int LG = 20;
const long long INF = 1e18 + 5;
const int C = 26;
const int B = 1000;
const int MOD = 998244353;
int n, a[N], b[N], cur, type, num;
pair<int, int> dp[N][2]; // range for the number of a[x] in there .-.
string s = "";
inline void solve()
{
cin >> n;
for (int x = 1; x <= 2 * n; x++)
{
cin >> a[x];
dp[x][0] = {-1, -1};
dp[x][1] = {-1, -1};
}
for (int x = 1; x <= 2 * n; x++)
{
cin >> b[x];
}
dp[1][0] = {1, 1};
dp[1][1] = {0, 0};
for (int x = 2; x <= 2 * n; x++)
{
if (a[x] >= a[x - 1] && a[x] >= b[x - 1])
{
if (dp[x - 1][0] == pair<int, int>{-1, -1})
dp[x][0] = dp[x - 1][1];
else if (dp[x - 1][1] == pair<int, int>{-1, -1})
dp[x][0] = dp[x - 1][0];
else
dp[x][0] = {min(dp[x - 1][0].first, dp[x - 1][1].first), max(dp[x - 1][0].second, dp[x - 1][1].second)};
if (dp[x][0].first != -1)
{
dp[x][0].first++;
dp[x][0].second++;
}
}
else if (a[x] >= a[x - 1])
{
dp[x][0] = dp[x - 1][0];
if (dp[x][0].first != -1)
{
dp[x][0].first++;
dp[x][0].second++;
}
}
else if (a[x] >= b[x - 1])
{
dp[x][0] = dp[x - 1][1];
if (dp[x][0].first != -1)
{
dp[x][0].first++;
dp[x][0].second++;
}
}
if (b[x] >= a[x - 1] && b[x] >= b[x - 1])
{
if (dp[x - 1][0] == pair<int, int>{-1, -1})
dp[x][1] = dp[x - 1][1];
else if (dp[x - 1][1] == pair<int, int>{-1, -1})
dp[x][1] = dp[x - 1][0];
else
dp[x][1] = {min(dp[x - 1][0].first, dp[x - 1][1].first), max(dp[x - 1][0].second, dp[x - 1][1].second)};
}
else if (b[x] >= a[x - 1])
{
dp[x][1] = dp[x - 1][0];
}
else if (b[x] >= b[x - 1])
{
dp[x][1] = dp[x - 1][1];
}
// cout << x << "\n";
// cout << dp[x][0].first << "|" << dp[x][0].second << "\n";
// cout << dp[x][1].first << "|" << dp[x][1].second << "\n";
}
cur = 2 * n;
num = n;
type = -1;
if (dp[2 * n][0].first <= n && n <= dp[2 * n][0].second)
{
type = 0;
}
if (dp[2 * n][1].first <= n && n <= dp[2 * n][1].second)
{
type = 1;
}
if (type == -1)
{
cout << -1;
return;
}
while (cur > 0)
{
if (type == 0)
{
num--;
s += 'A';
// cout << a[cur] << " ";
}
else
{
s += 'B';
// cout << b[cur] << " ";
}
// cout << num << " " << cur << " " << type << " " << dp[cur][type].first << " " << dp[cur][type].second << "\n";
if (cur == 1)
break;
if (type)
{
if (dp[cur - 1][0].first <= num && num <= dp[cur - 1][0].second && num > 0 && b[cur] >= a[cur - 1])
{
type = 0;
cur--;
}
else
{
type = 1;
cur--;
}
}
else
{
if (dp[cur - 1][0].first <= num && num <= dp[cur - 1][0].second && num > 0 && a[cur] >= a[cur - 1])
{
type = 0;
cur--;
}
else
{
type = 1;
cur--;
}
}
}
reverse(s.begin(), s.end());
cout << s << "\n";
// cout << num << "\n";
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
for (int x = 1; x <= t; x++)
{
solve();
}
return 0;
}
