#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define ii pair<ll, ll>
const long mxN = 5e5 + 7, inf = 1e9 + 7;
int tt[mxN], a[2][mxN], n, p[mxN], cur[mxN];
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
n *= 2;
for (int j = 0; j <= 1; j++)
{
for (int i = 1; i <= n; i++)
cin >> a[j][i];
}
for (int i = 1; i <= n; i++)
{
tt[i] = 2;
p[i] = 1;
if (a[0][i] > a[1][i])
{
swap(a[0][i], a[1][i]);
p[i] = -1;
}
}
int cnt = 0;
for (int i = 1; i <= n; i++)
{
cur[i] = a[0][i];
if (a[0][i] < cur[i - 1])
{
cur[i] = a[1][i];
tt[i] = 1;
cnt += p[i];
}
}
cur[n + 1] = inf;
for (int i = n; i >= 1; i--)
{
cur[i] = a[1][i];
if (a[1][i] > cur[i + 1])
{
cur[i] = a[0][i];
tt[i] = 0;
cnt -= p[i];
}
}
for (int i = 1; i <= n; i++)
{
if (tt[i] == 2)
{
if (abs(cnt + p[i]) <= abs(cnt - p[i]))
{
cnt += p[i];
tt[i] = 1;
}
else
{
cnt -= p[i];
tt[i] = 0;
}
}
if (a[tt[i - 1]][i - 1] > a[tt[i]][i])
{
cnt = 1;
break;
}
}
if (cnt)
{
cout << -1;
return 0;
}
for (int i = 1; i <= n; i++)
{
tt[i] ^= (p[i] != 1);
cout << char('A' + tt[i]);
}
}
