#include <bits/stdc++.h>
#define ff first
#define ss second
#define ALL(x) x.begin(),x.end()
using namespace std;
using PII = pair <int, int>;
int n;
const int N = 5e5 + 5;
const int M = 2 * N;
int a[M], b[M], ans[M]; // 0 ? A : B
const int INF = 1.07e9;
PII dp[M][2];
const PII zero = {-1, -1};
void merge(PII&a, PII b, int add) {
if (a == zero) {
if (b != zero) a = {b.ff+add, b.ss+add};
return;
}
if (b == zero) return;
a.ff = min(b.ff+add, a.ff);
a.ss = max(b.ss+add, a.ss);
}
signed main() {
// freopen("0.in", "r", stdin);
// freopen("0.out", "w", stdout);
ios::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];
dp[1][0] = {1, 1};
dp[1][1] = {0, 0};
for (int i = 2; i <= 2 * n; i++) {
dp[i][0] = dp[i][1] = zero;
if (a[i-1] <= a[i]) merge(dp[i][0], dp[i-1][0], 1);
if (b[i-1] <= a[i]) merge(dp[i][0], dp[i-1][1], 1);
if (a[i-1] <= b[i]) merge(dp[i][1], dp[i-1][0], 0);
if (b[i-1] <= b[i]) merge(dp[i][1], dp[i-1][1], 0);
}
// merge(dp[2*n][0], dp[2*n][1], 0);
if ((dp[2*n][0].ss < n && n < dp[2*n][0].ff) && (dp[2*n][1].ss < n && n < dp[2*n][1].ff)) {
cout << "-1\n";
return 0;
}
string ans = "";
int last = 0;
// for (int i = 1; i <= 2*n; i++) {
// cout << dp[i][0].ff << ',' << dp[i][0].ss << ' ' << dp[i][1].ff << ',' << dp[i][1].ss << '\n';
// }
if (dp[2*n][0].ff <= n && n <= dp[2*n][0].ss) last = 0;
else last = 1;
int target = n;
for (int i = 2 * n; i > 1; i--) {
ans.push_back('A'+last);
target -= last == 0;
// cout << ans << " " << last << ' ' << target << "\n";
if (last == 0) {
if (a[i-1] <= a[i] && dp[i-1][0] != zero && dp[i-1][0].ff <= target && target <= dp[i-1][0].ss) last = 0;
else last = 1;
} else {
if (a[i-1] <= b[i] && dp[i-1][0] != zero && dp[i-1][0].ff <= target && target <= dp[i-1][0].ss) last = 0;
else last = 1;
}
}
ans.push_back('A'+last);
target -= last == 0;
// cout << ans << " " << last << ' ' << target << "\n";
reverse(ALL(ans));
cout << ans << '\n';
}
