#define local
#ifndef local
#include ""
#endif
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
#define int long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;
const int N = 1e6 + 5;
const int oo = 1e18 + 7, mod = 1e9 + 7;
mt19937 rng(1);
int rnd(int l, int r){
int temp = rng() % (r - l + 1);
return abs(temp) + l;
}
int n, a[N], b[N];
int maxia[N][2], maxib[N][2];
#ifdef local
void process(){
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++) maxia[i][0] = maxia[i][1] = maxib[i][0] = maxib[i][1] = -oo;
maxia[2 * n][0] = maxib[2 * n][1] = 1;
maxia[2 * n][1] = maxib[2 * n][0] = 0;
for(int i = 2 * n - 1; i >= 1; i--){
for(int j = 0; j < 2; j++){
for(int lst = 0; lst < 2; lst++){
int temp1 = (!j ? a[i] : b[i]);
int temp2 = (!lst ? a[i + 1] : b[i + 1]);
if(temp1 > temp2) continue;
maxia[i][j] = max(maxia[i][j], maxia[i + 1][lst] + (j == 0));
maxib[i][j] = max(maxib[i][j], maxib[i + 1][lst] + (j == 1));
}
// cout << i << " " << j << " " << maxia[i][j] << " " << maxib[i][j] << "\n";
}
}
int temp = -1;
if(maxia[1][0] >= n && maxib[1][0] >= n) temp = 0;
if(maxia[1][1] >= n && maxib[1][1] >= n) temp = 1;
if(temp < 0){
cout << -1 << "\n";
return;
}
string s;
int aa = (temp == 0), bb = (temp == 1), lst = temp;
if(temp == 0) s += "A";
else s += "B";
for(int i = 2; i <= 2 * n; i++){
int tempo = (lst == 0 ? a[i - 1] : b[i - 1]);
if(a[i] < tempo){
bb++;
lst = 1;
s += "B";
}
else if(b[i] < tempo){
aa++;
lst = 0;
s += "A";
}
else if((maxia[i][0] >= n - aa) && (maxib[i][0] >= n - bb)){
aa++;
lst = 0;
s += "A";
}
else{
bb++;
lst = 1;
s += "B";
}
}
cout << s;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
process();
}
#endif
