// In the name of Allah
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef complex<ld> cld;
#define all(x) (x).begin(),(x).end()
#define len(x) ((ll) (x).size())
#define F first
#define S second
#define pb push_back
#define sep ' '
#define endl '\n'
#define Mp make_pair
#define kill(x) cout << x << '\n', exit(0)
#define set_dec(x) cout << fixed << setprecision(x);
#define file_io(x,y) freopen(x, "r", stdin); freopen(y, "w", stdout);
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxn = 1e6 + 7;
const int oo = 1e9 + 4;
int n; pll A[maxn];
pii dp[maxn][2];
vector<char> res;
void solve() {
cin >> n; n *= 2;
for (int i = 0; i < n; i++) cin >> A[i].F;
for (int i = 0; i < n; i++) cin >> A[i].S;
for (int i = 0; i < n; i++) {
if (i == 0) {
dp[i][0] = Mp(0, 0); dp[i][1] = Mp(1, 1);
}
else {
dp[i][0] = dp[i][1] = Mp(oo, -oo);
if (A[i].F >= A[i - 1].F) {
pii f = dp[i - 1][0];
dp[i][0].F = min(dp[i][0].F, f.F);
dp[i][0].S = max(dp[i][0].S, f.S);
}
if (A[i].F >= A[i - 1].S) {
pii f = dp[i - 1][1];
dp[i][0].F = min(dp[i][0].F, f.F);
dp[i][0].S = max(dp[i][0].S, f.S);
}
if (A[i].S >= A[i - 1].F) {
pii f = dp[i - 1][0];
dp[i][1].F = min(dp[i][1].F, f.F + 1);
dp[i][1].S = max(dp[i][1].S, f.S + 1);
}
if (A[i].S >= A[i - 1].S) {
pii f = dp[i - 1][1];
dp[i][1].F = min(dp[i][1].F, f.F + 1);
dp[i][1].S = max(dp[i][1].S, f.S + 1);
}
}
}
int j = n - 1, R = -1, x = (n / 2);
if (dp[n - 1][0].F <= x && dp[n - 1][0].S >= x) R = 0;
else if (dp[n - 1][1].F <= x && dp[n - 1][1].S >= x) R = 1;
else {
cout << -1 << endl;
return ;
}
while (true) {
if (R == 0) res.pb('A');
else {
res.pb('B'); x--;
}
if (j == 0) break;
int valx = (R == 0) ? A[j].F : A[j].S;
if (A[j - 1].F <= valx && dp[j - 1][0].F <= x && dp[j - 1][0].S >= x) {
j--; R = 0;
}
else {
j--; R = 1;
}
}
reverse(all(res));
for (int i = 0; i < n; i++) cout << res[i];
cout << endl;
}
int main() {
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int T = 1;
while (T--) {
solve();
}
return 0;
}
