#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];
void shift(int);
pair<int,int> get(int id, int L, int R, int x){
if (seg[id] > x)
return {-1,-1};
if (L+1 == R)
return {L,R};
shift(id);
int mid = (L + R) >> 1;
auto it1 = get(2*id+0, L, mid, x);
auto it2 = get(2*id+1, mid, R, x);
if (it1 == make_pair(-1,-1))
return it2;
if (it2 == make_pair(-1,-1))
return it1;
return {it1.first, it2.second};
}
void change(int id, int L, int R, int l, int r, int val){
if (r <= L or R <= l)
return;
if (l <= L and R <= r){
seg[id] = val;
lazy[id] = val;
return;
}
shift(id);
int mid = (L + R) >> 1;
change(2*id+0, L, mid, l, r, val);
change(2*id+1, mid, R, l, r, val);
seg[id] = min(seg[2*id+0], seg[2*id+1]);
}
void shift(int id){
if (lazy[id] == 0)
return;
change(2*id+0, 0, 1, 0, 1, lazy[id]);
change(2*id+1, 0, 1, 0, 1, lazy[id]);
lazy[id] = 0;
}
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, 1, 2*n+1, inf);
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;
}
