#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define pii pair<int, int>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) ((1ll << (x)))
#define debug(a, l, r) for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';
const int MAXN = 1e6 + 6;
const int INF = 1e18 + 7;
int n, a[MAXN][2], dpmx[MAXN][2], dpmi[MAXN][2];
void init() {
cin >> n; n *= 2;
for (int i = 1; i <= n; ++i) cin >> a[i][0];
for (int i = 1; i <= n; ++i) cin >> a[i][1];
}
void solve() {
dpmx[1][0] = dpmi[1][0] = 1;
dpmx[1][1] = dpmi[1][1] = -1;
for (int i = 2; i <= n; ++i) {
for (int cur = 0; cur < 2; ++cur) {
dpmx[i][cur] = -INF; dpmi[i][cur] = INF;
for (int pre = 0; pre < 2; ++pre) {
int weight = (cur == 0 ? 1 : -1);
if (a[i - 1][pre] <= a[i][cur]) {
if (dpmx[i - 1][pre] != -INF) dpmx[i][cur] = max(dpmx[i][cur], dpmx[i - 1][pre] + weight);
if (dpmi[i - 1][pre] != INF) dpmi[i][cur] = min(dpmi[i][cur], dpmi[i - 1][pre] + weight);
}
}
}
// cout << dpmi[i][0] << ' ' << dpmx[i][0] << '\n';
// cout << dpmi[i][1] << ' ' << dpmx[i][1] << '\n';
// cout << '\n';
}
// Trace
int en = -1;
if (dpmi[n][0] <= 0 && 0 <= dpmx[n][0]) en = 0;
else if (dpmi[n][1] <= 0 && 0 <= dpmx[n][1]) en = 1;
if (en == -1) {
cout << -1;
return;
}
int sum = 0, pos = n, state = en;
vector<int> res;
while (pos >= 1) {
res.push_back(state);
int weight = (state == 0 ? 1 : -1);
sum -= weight;
--pos;
if (a[pos][0] <= a[pos+1][state] && dpmi[pos][0] <= sum && sum <= dpmx[pos][0]) state = 0;
else if (a[pos][1] <= a[pos+1][state] && dpmi[pos][1] <= sum && sum <= dpmx[pos][1]) state = 1;
}
reverse(all(res));
for (int u : res) cout << (u ? 'B' : 'A');
}
signed main() {
#ifdef NCTHANH
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
init();
solve();
return 0;
}
