#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define se second
#define fi first
#define ll long long
#define ii pair<ll, ll>
const long mxN = 1e6 + 7, inf = 1e9 + 7;
int a[mxN][2], n;
ii dp[mxN][2];
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
cin >> n;
for (int i = 0; i <= 1; i++)
{
for (int j = 1; j <= n * 2; j++)
cin >> a[j][i];
}
for (int j = 1; j <= n * 2; j++)
{
for (int i = 0; i <= 2; i++)
{
dp[j][i] = {inf, -inf};
for (int u = 0; u <= 1; u++)
{
if (a[j - 1][u] <= a[j][i])
{
dp[j][i].fi = min(dp[j][i].fi, dp[j - 1][u].fi + i);
dp[j][i].se = max(dp[j][i].se, dp[j - 1][u].se + i);
}
}
}
}
if (!(dp[n * 2][0].fi <= n && n <= dp[n * 2][0].se) && !(dp[n * 2][1].fi <= n && n <= dp[n * 2][1].se))
{
cout << -1;
return 0;
}
bool cur = 0;
int cnt = n;
a[n * 2 + 1][0] = inf;
string ans;
for (int i = n * 2; i >= 1; i--)
{
for (int j = 0; j <= 1; j++)
{
if (a[i + 1][cur] >= a[i][j] && dp[i][j].fi <= cnt && cnt <= dp[i][j].se)
{
cur = j;
break;
}
}
ans += 'A' + cur;
cnt -= cur;
}
reverse(ans.begin(), ans.end());
cout << ans;
}
