#include <bits/stdc++.h>
using namespace std;
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int n;
cin >> n;
vector<int> a(2*n+1);
vector<int> b(2*n+1);
vector<pair<int,int>> wow(2*n+1,{1e9,0});
vector<pair<int,int>> wut(2*n+1,{1e9,0});
for(int i = 1; i <= 2*n; i++) {
cin >> a[i];
}
for(int i = 1; i <= 2*n; i++) {
cin >> b[i];
}
wow[0] = {0,0};
wut[0] = {0,0};
for(int i = 1; i <= 2*n; i++) {
if(a[i] >= a[i-1]) {
wow[i] = {wow[i-1].first+1,wow[i-1].second+1};
}
if(a[i] >= b[i-1]) {
wow[i] = {min(wow[i].first,wut[i-1].first+1),max(wow[i].second,wut[i-1].second+1)};
}
if(b[i] >= a[i-1]) {
wut[i] = {wow[i-1].first,wow[i-1].second};
}
if(b[i] >= b[i-1]) {
wut[i] = {min(wut[i].first,wut[i-1].first),max(wut[i].second,wut[i-1].second)};
}
}
string ans = "";
int x = -1,br = n;
if(wow[2*n].second >= n && wow[2*n].first <= n) {
x = 0;
ans = "A";
br--;
}
else if(wut[2*n].second >= n && wut[2*n].first <= n) {
x = 1;
ans = "B";
}
if(x == -1) {
cout << -1 << "\n";
}
else {
for(int i = 2*n-1; i >= 1; i--) {
int c;
if(x == 0) {
c = a[i+1];
}
else {
c = b[i+1];
}
if(wow[i].second >= br && wow[i].first <= br && a[i] <= c) {
ans+='A';
x = 0;
br--;
}
else {
ans+='B';
x = 1;
}
}
reverse(ans.begin(),ans.end());
cout << ans;
}
return 0;
}
