#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pi;
int N, num[2][1000005];
int fix[1000005];
int curchar[1000005];
int linkend[1000005], linkchange[1000005];
int lowminpref, lowmaxsuff;
vector<pi> chains[1000005];
vector<int> flippos;
void die(){
cout << -1 << '\n';
exit(0);
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> N;
for (int i = 1; i <= 2*N; ++i){
cin >> num[0][i];
}
for (int i = 1; i <= 2*N; ++i){
cin >> num[1][i];
}
num[0][2*N+1] = num[1][2*N+1] = 1e9+10;
for (int i = 1; i <= 2*N; ++i){
fix[i] = -1;
}
for (int i = 1; i <= 2*N; ++i){
//cerr << i << '\n';
if (num[0][i] < lowminpref && num[1][i] < lowminpref){
die();
}
else if (num[0][i] >= lowminpref && num[1][i] < lowminpref){
fix[i] = 0;
lowminpref = num[0][i];
}
else if (num[0][i] < lowminpref && num[1][i] >= lowminpref){
fix[i] = 1;
lowminpref = num[1][i];
}
else{
lowminpref = max(lowminpref,min(num[0][i],num[1][i]));
}
}
lowmaxsuff = 1e9+10;
for (int i = 2*N; i >= 1; --i){
//cerr << i << '\n';
if (num[0][i] > lowmaxsuff && num[1][i] > lowmaxsuff){
die();
}
else if (num[0][i] <= lowmaxsuff && num[1][i] > lowmaxsuff){
if (fix[i] == 1) die();
fix[i] = 0;
lowmaxsuff = num[0][i];
}
else if (num[0][i] > lowmaxsuff && num[1][i] <= lowmaxsuff){
if (fix[i] == 0) die();
fix[i] = 1;
lowmaxsuff = num[1][i];
}
else{
if (fix[i] != -1) lowmaxsuff = min(lowmaxsuff,num[fix[i]][i]);
else lowmaxsuff = min(lowmaxsuff,max(num[0][i],num[1][i]));
}
}
int as = 0;
for (int i = 1; i <= 2*N; ++i){
if (fix[i] != -1) curchar[i] = fix[i];
else{
if (num[0][i] <= num[1][i]) curchar[i] = 0;
else curchar[i] = 1;
}
if (curchar[i] == 0) as++;
}
for (int i = 2*N; i >= 1; --i){
if (fix[i] == -1){
linkend[i] = i;
linkchange[i] = (curchar[i] == 0 ? -1 : 1);
if (num[1-curchar[i]][i] > num[curchar[i+1]][i+1]){
linkend[i] = linkend[i+1];
linkchange[i] += linkchange[i+1];
}
chains[linkend[i]].push_back(pi(linkchange[i],i));
}
}
for (int i = 1; i <= 2*N; ++i){
chains[i].push_back(pi(0,1e9));
sort(chains[i].begin(),chains[i].end());
}
if (as < N){
for (int i = 1; i <= 2*N; ++i){
reverse(chains[i].begin(),chains[i].end());
}
}
//cerr << as << '\n';
int diff = 0;
for (int i = 1; i <= 2*N; ++i){
if (as + diff == N) break;
if (chains[i].size()){
if (as < N){
if (as + diff + chains[i][0].first >= N){
for (auto it : chains[i]){
if (as + diff + it.first == N){
flippos.push_back(it.second);
diff += it.first;
break;
}
}
}
else{
diff += chains[i][0].first;
flippos.push_back(chains[i][0].second);
}
}
else if (as > N){
if (as + diff + chains[i][0].first <= N){
for (auto it : chains[i]){
if (as + diff + it.first == N){
flippos.push_back(it.second);
diff += it.first;
break;
}
}
}
else{
diff += chains[i][0].first;
flippos.push_back(chains[i][0].second);
}
}
}
}
//cerr << as << '\n';
if (as + diff != N) die();
for (auto it : flippos){
if (it == 1e9) continue;
int x = it;
while (x != linkend[x]){
curchar[x] = 1 - curchar[x];
x++;
}
curchar[x] = 1 - curchar[x];
}
for (int i = 1; i <= 2*N; ++i){
if (curchar[i] == 0) cout << 'A';
else cout << 'B';
}
cout << '\n';
}
/*
3
2 5 4 9 15 11
6 7 6 8 12 14
2
1 4 10 20
3 5 8 13
2
3 4 5 6
10 9 8 7
6
25 18 40 37 29 95 41 53 39 69 61 90
14 18 22 28 18 30 32 32 63 58 71 78
6
14 18 22 28 18 30 32 32 63 58 71 78
25 18 40 37 29 95 41 53 39 69 61 90
BABBABAABABA
ABAABABBABAB
*/
