#include<bits/stdc++.h>
using namespace std;
const int MAXN = 4005;
const int INF = 1e9 + 5;
int n;
int a[MAXN];
int b[MAXN];
bool dp[MAXN][MAXN][2];
vector<char> peal;
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
for (int i = 1; i <= 2 * n; i++) cin >> a[i];
for (int i = 1; i <= 2 * n; i++) cin >> b[i];
a[0] = -INF;
b[0] = -INF;
memset(dp, false, sizeof dp);
dp[0][0][0] = true;
dp[0][0][1] = true;
for (int i = 1; i <= 2 * n; i++)
{
for (int j = 0; j <= min(n, i); j++)
{
if (j >= 1)
{
if (a[i-1] <= a[i] && dp[i-1][j-1][0]) dp[i][j][0] = true;
if (b[i-1] <= a[i] && dp[i-1][j-1][1]) dp[i][j][0] = true;
}
if (a[i-1] <= b[i] && dp[i-1][j][0]) dp[i][j][1] = true;
if (b[i-1] <= b[i] && dp[i-1][j][1]) dp[i][j][1] = true;
}
}
if (!dp[2*n][n][0] && !dp[2*n][n][1])
{
cout << -1;
return 0;
}
int i = 2 * n, j = n, last = dp[2*n][n][0] ? 0 : 1;
while (i > 0)
{
if (last == 0)
{
peal.push_back('A');
i--;
j--;
if (dp[i][j][0]) last = 0;
else last = 1;
}
else
{
peal.push_back('B');
i--;
if (dp[i][j][0]) last = 0;
else last = 1;
}
}
reverse(peal.begin(), peal.end());
for (char v : peal) cout << v;
}
