#include <bits/stdc++.h>
using namespace std;
int N;
int A[1100100];
int B[1100100];
pair<int,int> big[1100100];
pair<int,int> small[1100100];
pair<int,int> onion(pair<int,int> ii, pair<int,int> ii1){
if(ii.first == -1) return ii1;
if(ii1.first == -1) return ii;
return {min(ii.first,ii1.first),max(ii.second,ii1.second)};
}
int main(){
scanf(" %d",&N);
for(int i = 0; i < N * 2; i++){
scanf(" %d",&A[i]);
}
for(int i = 0; i < N * 2; i++){
scanf(" %d",&B[i]);
}
bool die = false;
big[0] = {0,0};
small[0] = {1,1};
if(A[0] > B[0]) swap(big[0],small[0]);
for(int i = 1; i < N * 2; i++){
if(max(A[i],B[i]) < min(A[i - 1], B[i - 1]) ){
die = true;
break;
}
if(max(A[i - 1], B[i - 1]) <= B[i]){
if(small[i - 1].first == -1){
big[i] = big[i - 1];
}
else{
big[i] = {min(big[i - 1].first, small[i - 1].first), max(big[i - 1].second, small[i - 1].second )};
}
}
else if(min(A[i - 1], B[i - 1]) <= B[i]){
big[i] = small[i - 1];
}
else big[i] = {-1,-1};
if(max(A[i - 1], B[i - 1]) <= A[i]){
if(small[i - 1].first == -1){
small[i] = big[i - 1];
}
else{
small[i] = {min(big[i - 1].first, small[i - 1].first), max(big[i - 1].second, small[i - 1].second )};
}
small[i].first++;
small[i].second++;
}
else if(min(A[i - 1], B[i - 1]) <= A[i]){
small[i] = small[i - 1];
small[i].first++;
small[i].second++;
}
else small[i] = {-1,-1};
if(B[i] < A[i]) swap(big[i],small[i]);
}
if(die){
printf("-1\n");
}
else{
pair<int,int> ii = onion(big[N * 2 - 1], small[N * 2 - 1]);
if(N < ii.first || ii.second < N ){
printf("-1\n");
}
else{
int num = N;
vector<char> ans;
for(int i = N * 2 - 1; i >= 0; i--){
if(small[i].first <= num && num <= small[i].second){
if(A[i] <= B[i]){
ans.push_back('A');
num--;
}
else ans.push_back('B');
}
else{
if(A[i] > B[i]){
ans.push_back('A');
num--;
}
else ans.push_back('B');
}
}
reverse(ans.begin(),ans.end());
for(char c : ans) printf("%c",c);
}
}
}
