#include <bits/stdc++.h>
// #include <ext/rope>
// #include <ext/pb_ds/assoc_container.hpp>
// using namespace __gnu_pbds;
// using namespace __gnu_cxx;
using namespace std;
// #define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ll long long
#define ull unsigned long long
#define ld long double
#define pb push_back
#define bit(mask, i) ((mask >> i) & 1)
#define el '\n'
#define F first
#define S second
template <class X, class Y> bool maximize(X &x, const Y &y) { return (x < y ? x = y, 1 : 0); }
template <class X, class Y> bool minimize(X &x, const Y &y) { return (x > y ? x = y, 1 : 0); }
const int INF = 1e9;
const ll LINF = 1e18;
const int MOD = 1e9 + 7;
const int MULTI = 0;
const ld eps = 1e-9;
const int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0}; // R D L U
const int ddx[4] = {-1, 1, 1, -1}, ddy[4] = {1, 1, -1, -1}; // UR DR DL UL
const char cx[4] = {'R', 'D', 'L', 'U'};
const ll base = 31;
const int nMOD = 2;
const ll mods[] = {(ll)1e9 + 10777, (ll)1e9 + 19777, (ll)1e9 + 3, (ll)1e9 + 3777};
const int N = 5e5 + 5;
int n, a[N << 1], b[N << 1];
pair<int, int> dp[N << 1][2];
void trace(int i, int j, int cur) {
if (i == 0) return;
if (j == 0) {
cur--;
if (a[i - 1] <= a[i] && dp[i - 1][0].F <= cur && dp[i - 1][0].S >= cur)
trace(i - 1, 0, cur);
else
trace(i - 1, 1, cur);
cout << 'A';
} else {
if (a[i - 1] <= b[i] && dp[i - 1][0].F <= cur && dp[i - 1][0].S >= cur)
trace(i - 1, 0, cur);
else
trace(i - 1, 1, cur);
cout << 'B';
}
}
void solve() {
cin >> n;
for (int i = 1; i <= 2 * n; ++i)
cin >> a[i];
for (int i = 1; i <= 2 * n; ++i)
cin >> b[i];
for (int i = 1; i <= 2 * n; ++i) {
dp[i][0].F = dp[i][1].F = INF;
dp[i][0].S = dp[i][1].S = -INF;
}
for (int i = 0; i < 2 * n; ++i) {
if (a[i] <= a[i + 1]) {
minimize(dp[i + 1][0].F, dp[i][0].F + 1);
maximize(dp[i + 1][0].S, dp[i][0].S + 1);
}
if (a[i] <= b[i + 1]) {
minimize(dp[i + 1][1].F, dp[i][0].F);
maximize(dp[i + 1][1].S, dp[i][0].S);
}
if (b[i] <= a[i + 1]) {
minimize(dp[i + 1][0].F, dp[i][1].F + 1);
maximize(dp[i + 1][0].S, dp[i][1].S + 1);
}
if (b[i] <= b[i + 1]) {
minimize(dp[i + 1][1].F, dp[i][1].F);
maximize(dp[i + 1][1].S, dp[i][1].S);
}
}
if (dp[2 * n][0].F <= n && dp[2 * n][0].S >= n)
return trace(2 * n, 0, n), void();
if (dp[2 * n][1].F <= n && dp[2 * n][1].S >= n)
return trace(2 * n, 1, n), void();
cout << -1;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (!MULTI) solve();
else {
int test; cin >> test;
while (test--) solve();
}
return 0;
}
