//#pragma GCC optimize("Ofast,O2,O3,unroll-loops")
//#pragma GCC target("avx2")
#include <bits/stdc++.h>
using namespace std;
void debug_out() { cerr << endl; }
template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << "[" << H << "]";
debug_out(T...);
}
#ifdef dddxxz
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
#define SZ(s) ((int)s.size())
#define all(x) (x).begin(), (x).end()
#define lla(x) (x).rbegin(), (x).rend()
#define bpc(x) __builtin_popcount(x)
#define bpcll(x) __builtin_popcountll(x)
#define MP make_pair
clock_t startTime;
int getCurrentTime() {
return int((double) (clock() - startTime) / CLOCKS_PER_SEC * 1000);
}
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
typedef long long ll;
const int MOD = 998244353;
const int INF = 1000000101;
const long long LLINF = 1223372000000000555;
const int N = 1e6 + 3e2;
int a[N], b[N];
int dpl[N][2], pl[N][2];
int dpr[N][2], pr[N][2];
bool chmin(int &x, int y){
if (x <= y) return false;
x = y;
return true;
}
bool chmax(int &x, int y){
if (x >= y) return false;
x = y;
return true;
}
void solve(int TC) {
int n;
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++){
dpl[i][0] = dpl[i][1] = INF;
dpr[i][0] = dpr[i][1] = -INF;
pl[i][0] = pl[i][1] = -1;
pr[i][0] = pr[i][1] = -1;
}
dpl[1][0] = 1;
dpl[1][1] = 0;
dpr[1][0] = 1;
dpr[1][1] = 0;
for (int i = 2; i <= 2 * n; i++){
if (a[i] >= a[i - 1]){
if (chmin(dpl[i][0], dpl[i - 1][0] + 1)) pl[i][0] = 0;
if (chmax(dpr[i][0], dpr[i - 1][0] + 1)) pr[i][0] = 0;
}
if (a[i] >= b[i - 1]){
if (chmin(dpl[i][0], dpl[i - 1][1] + 1)) pl[i][0] = 1;
if (chmax(dpr[i][0], dpr[i - 1][1] + 1)) pr[i][0] = 1;
}
if (b[i] >= a[i - 1]){
if (chmin(dpl[i][1], dpl[i - 1][0])) pl[i][1] = 0;
if (chmax(dpr[i][1], dpr[i - 1][0])) pr[i][1] = 0;
}
if (b[i] >= b[i - 1]){
if (chmin(dpl[i][1], dpl[i - 1][1])) pl[i][1] = 1;
if (chmax(dpr[i][1], dpr[i - 1][1])) pr[i][1] = 1;
}
}
int i = 2 * n;
int x = -1;
if (dpl[2 * n][0] <= n && n <= dpr[2 * n][0]) x = 0;
if (dpl[2 * n][1] <= n && n <= dpr[2 * n][1]) x = 1;
if (x == -1){
cout << -1;
return;
}
string s;
if (x == 0){
s += 'A';
n--;
} else {
s += 'B';
}
while (i > 1){
int y = pl[i][x];
if (y == 0){
s += 'A';
n--;
} else {
s += 'B';
}
x = y;
i--;
}
reverse(all(s));
cout << s << endl;
}
int main() {
startTime = clock();
ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#ifdef dddxxz
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
int TC = 1;
//cin >> TC;
for (int test = 1; test <= TC; test++) {
//debug(test);
//cout << "Case #" << test << ": ";
solve(test);
}
#ifdef dddxxz
cerr << endl << "Time: " << getCurrentTime() << " ms" << endl;
#endif
return 0;
}
