#include <iostream>
#include <cstdio>
#include <vector>
//maksimumi i minimumi su rastuci
// a +1 b -1
using namespace std;
#define ss second
#define ff first
#define mp make_pair
#define pb push_back
#define ll long long
const int N = 1e6+11;
int n;
int a[N], b[N];
int res;
vector <int> v[N];
vector <int> s1[N];
vector <int> s2[N];
vector <int> koji1[N];
vector <int> koji2[N];
int mali[N];
int veliki[N];
int br;
int uzeo[N];
int sol[N];
void ne() {
cout << -1;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
for (int i=0;i<2*n;i++) {
cin >> a[i];
}
for (int i=0;i<2*n;i++) {
cin >> b[i];
}
int mini = min(a[0], b[0]);
for (int i=1;i<2*n;i++) {
if (a[i] < mini && b[i] < mini) {
ne();
return 0;
}
if (a[i] < mini) {
a[i] = -1;
mini = b[i];
}
else if (b[i] < mini) {
b[i] = -1;
mini = a[i];
}
else {
mini = min(a[i], b[i]);
}
}
int maksi = max(a[2*n-1], b[2*n-1]);
for (int i=2*n-2; i >= 0; i--) {
if (a[i] > maksi && b[i] > maksi) {
ne();
return 0;
}
if (a[i] > maksi) {
a[i] = -1;
maksi = b[i];
}
else if (b[i] > maksi) {
b[i] = -1;
maksi = a[i];
}
else {
maksi = max(a[i], b[i]);
}
if (a[i] == -1 && b[i] == -1) {
ne();
return 0;
}
}
int a1 = 1e9+1, b1 = 1e9+1;
for (int i=0;i<2*n;i++) {
if (a[i] == -1) res -= 1;
else if (b[i] == -1) res += 1;
else {
if (a1 <= a[i] && a1 <= b[i] && b1 <= a[i] && b1 <= b[i]) {
br++;
v[br].pb(i);
a1 = a[i];
b1 = b[i];
}
else {
v[br].pb(i);
a1 = a[i];
b1 = b[i];
}
}
}
br++;
for (int i=0;i<br;i++) {
int siz = v[i].size();
for (int j=0;j<siz;j++) {
int x = v[i][j];
if (a[x] < b[x]) {
s1[i].pb(1);
koji1[i].pb(1);
s2[i].pb(-1);
koji2[i].pb(-1);
}
else {
s1[i].pb(-1);
koji1[i].pb(-1);
s2[i].pb(1);
koji2[i].pb(1);
}
}
for (int j=1;j<siz;j++) {
s1[i][j] += s1[i][j-1];
}
for (int j=siz-2;j>=0;j--) {
s2[i][j] += s2[i][j+1];
}
int manji, veci;
veci = max(s2[i][0], s1[i][siz-1]);
manji = min(s2[i][0], s1[i][siz-1]);
for (int j=1;j<siz;j++) {
int sada = s2[i][j] + s1[i][j-1];
veci = max(sada, veci);
manji = min(sada, manji);
}
mali[i] = manji;
veliki[i] = veci;
uzeo[i] = manji;
res += manji;
}
if (res % 2 == 1 || res > 0) {
ne();
return 0;
}
for (int i=0;i<br;i++) {
int uzmi = veliki[i] - mali[i];
uzmi = min(uzmi, -res);
uzeo[i] = mali[i] + uzmi;
res += uzmi;
}
if (res != 0) {
ne();
return 0;
}
for (int i=0;i<br;i++) {
int siz = v[i].size();
int c = uzeo[i];
if (s1[i][siz-1] == c) {
for (int j=0;j<siz;j++) {
sol[v[i][j]] = koji1[i][j];
}
continue;
}
if (s2[i][0] == c) {
for (int j=0;j<siz;j++) {
sol[v[i][j]] = koji2[i][j];
}
continue;
}
for (int j=1;j<siz;j++) {
if (s2[i][j] + s1[i][j-1] == c) {
for (int k=0;k<j;k++) {
sol[v[i][k]] = koji1[i][k];
}
for (int k=j;k<siz;k++) {
sol[v[i][k]] = koji2[i][k];
}
break;
}
}
}
for (int i=0;i<2*n;i++) {
if (a[i] == -1) cout << "B";
else if (b[i] == -1) cout << "A";
else if (sol[i] == -1) cout << "B";
else if (sol[i] == 1) cout << "A";
}
return 0;
}
