#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e6 + 10;
const int inf = 1e9 + 1;
int a[maxn], b[maxn];
pair<int,int> A[maxn], B[maxn];
int seg[4*maxn], lazy[4*maxn];
vector<pair<int,pair<int,int>>> vec;
pair<int,int> get(int id, int L, int R, int x){
pair<int,int> ret = {-1,-1};
for (auto it : vec){
if (it.first > x)
continue;
if (ret == make_pair(-1,-1))
ret = it.second;
else{
ret.first = min(ret.first, it.second.first);
ret.second = max(ret.second, it.second.second);
}
}
return ret;
}
void change(int id, int L, int R, int l, int r, int val){
if (val == inf){
vec.clear();
return;
}
vec.push_back({val,{l,r}});
}
int main(){
ios_base::sync_with_stdio(false);
int n;
cin >> n;
for (int i = 0; i < 2*n; i++)
cin >> a[i];
for (int i = 0; i < 2*n; i++)
cin >> b[i];
for (int i = 1; i < 2*n; i++)
if (max(a[i],b[i]) < min(a[i-1],b[i-1]))
return cout << -1 << endl, 0;
change(1, 0, 2*n+1, 0, 1, 0);
for (int i = 0; i < 2*n; i++){
auto ita = get(1, 0, 2*n+1, a[i]);
auto itb = get(1, 0, 2*n+1, b[i]);
A[i] = ita, B[i] = itb;
if (ita == make_pair(-1,-1) and itb == make_pair(-1,-1))
return cout << -1 << endl, 0;
if (a[i] < b[i]){
if (ita == make_pair(-1,-1)){
change(1, 0, 2*n+1, 0, 2*n+1, inf);
change(1, 0, 2*n+1, itb.first+1, itb.second+1, b[i]);
continue;
}
change(1, 0, 2*n+1, 0, 2*n+1, inf);
change(1, 0, 2*n+1, itb.first+1, itb.second+1, b[i]);
change(1, 0, 2*n+1, ita.first, ita.second, a[i]);
}
else{
if (itb == make_pair(-1,-1)){
change(1, 0, 2*n+1, 0, 2*n+1, inf);
change(1, 0, 2*n+1, ita.first, ita.second, a[i]);
continue;
}
change(1, 0, 2*n+1, 0, 2*n+1, inf);
change(1, 0, 2*n+1, ita.first, ita.second, a[i]);
change(1, 0, 2*n+1, itb.first+1, itb.second+1, b[i]);
}
}
auto it = get(1, 0, 2*n+1, inf-1);
if (it.first == -1 or it.first > n or it.second <= n)
return cout << -1 << endl, 0;
int now = n;
string s;
int last = inf;
for (int i = 2*n-1; i >= 0; i--){
if (b[i] <= last and (A[i].first == -1 or A[i].first > now or A[i].second <= now or a[i] > last)){
s += 'B';
now --;
last = b[i];
continue;
}
s += 'A';
last = a[i];
}
reverse(s.begin(),s.end());
cout << s << endl;
}
