#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define f1 first
#define s2 second
#define fastio ios :: sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define debug(x) cerr << "[" << #x << "]: " << x << "\n";
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using pl = pair<ll, ll>;
constexpr ld PI = 4*atan((ld)1);
constexpr int MAX = 1e6 + 69;
int n;
int a[MAX], b[MAX];
ii dp[MAX][2];
ii merge(ii p, ii q)
{
if (q == mp(1, 0)) return p;
if (p == mp(1, 0)) return q;
return {min(p.f1, q.f1), max(p.s2, q.s2)};
}
void rc(int i, int ty, int rem)
{
if (i == 0) return;
if (dp[i-1][0].f1 <= rem && rem <= dp[i-1][0].s2 && a[i-1] <= (ty ? b[i] : a[i])) rc(i-1, 0, rem);
else rc(i-1, 1, rem - 1);
cout << (ty ? 'B' : 'A');
}
int main()
{
fastio;
cin >> n;
for (int i = 1; i <= 2*n; ++i)
cin >> a[i];
for (int i = 1; i <= 2*n; ++i)
cin >> b[i];
dp[1][0] = {0, 0};
dp[1][1] = {1, 1};
for (int i = 2; i <= 2*n; ++i)
{
{
dp[i][0] = {1, 0};
if (a[i-1] <= a[i]) dp[i][0] = merge(dp[i][0], dp[i-1][0]);
if (b[i-1] <= a[i]) dp[i][0] = merge(dp[i][0], dp[i-1][1]);
}
{
dp[i][1] = {1, 0};
if (a[i-1] <= b[i]) dp[i][1] = merge(dp[i][1], dp[i-1][0]);
if (b[i-1] <= b[i]) dp[i][1] = merge(dp[i][1], dp[i-1][1]);
if (dp[i][1] != mp(1, 0))
dp[i][1].f1++, dp[i][1].s2++;
}
}
if (dp[2*n][0].f1 <= n && n <= dp[2*n][0].s2) rc(2*n, 0, n);
else if (dp[2*n][1].f1 <= n && n <= dp[2*n][1].s2) rc(2*n, 1, n-1);
else cout << -1;
cout << '\n';
return 0;
}
