#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
#define endl "\n"
typedef long long ll;
template<class T, class T2> inline ostream &operator <<(ostream &out, const pair<T, T2> &x) { out << x.first << " " << x.second; return out;}
template<class T, class T2> inline istream &operator >>(istream &in, pair<T, T2> &x) { in >> x.first >> x.second; return in;}
template<class T, class T2> inline bool chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline bool chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
const ll mod = 1e9 + 7;
#define out(x) "{" << (#x) << ": " << x << "} "
const int MAX_N = 4e3 + 10;
int n, a[MAX_N], b[MAX_N];
int dp[MAX_N][MAX_N][2];
bool hist[MAX_N][MAX_N][2];
void output(int x, int y, int last) {
if(x == -1) {return;}
output(x - 1, y - last, hist[x][y][last]);
if(last) {
cout << "B";
} else {
cout << "A";
}
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n;
n *= 2;
for(int i = 0; i < n; i ++) {
cin >> a[i];
}
for(int i = 0; i < n; i ++) {
cin >> b[i];
}
dp[0][0][0] = 1;
dp[0][1][1] = 1;
for(int i = 0; i < n; i ++) {
for(int j = 0; j < n; j ++) {
if(dp[i][j][0]) {
int now = a[i];
if(now <= a[i + 1]) {
dp[i + 1][j][0] = 1;
hist[i + 1][j][0] = 0;
}
if(now <= b[i + 1]) {
dp[i + 1][j + 1][1] = 1;
hist[i + 1][j + 1][1] = 0;
}
}
if(dp[i][j][1]) {
int now = b[i];
if(now <= a[i + 1]) {
dp[i + 1][j][0] = 1;
hist[i + 1][j][0] = 1;
}
if(now <= b[i + 1]) {
dp[i + 1][j + 1][1] = 1;
hist[i + 1][j + 1][1] = 1;
}
}
}
}
for(int i = 0; i < n; i ++) {
bool on = false, bad = false;
for(int j = 0; j < n; j ++) {
if(dp[i][j][0]) {
if(bad) {
assert(false);
}
on = true;
} else if(on) {
bad = true;
}
}
}
for(int i = 0; i < n; i ++) {
bool on = false, bad = false;
for(int j = 0; j < n; j ++) {
if(dp[i][j][1]) {
if(bad) {
assert(false);
}
on = true;
} else if(on) {
bad = true;
}
}
}
if(!dp[n - 1][n / 2][0] && !dp[n - 1][n / 2][1]) {
cout << -1 << endl;
} else if(dp[n - 1][n / 2][1]) {
output(n - 1, n / 2, 1);
} else {
output(n - 1, n / 2, 0);
}
return 0;
for(int i = 0; i < n; i ++) {
for(int j = 0; j < n; j ++) {
cout << dp[i][j][0] << " ";
}
cout << endl;
}
cout << endl;
for(int i = 0; i < n; i ++) {
for(int j = 0; j < n; j ++) {
cout << dp[i][j][1] << " ";
}
cout << endl;
}
return 0;
}
