#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define pb push_back
#define ff first
#define ss second
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define int long long
const int N = 1e6+5, inf = 1e16, mod = 1e9+7;
template <class F, class _S>
bool chmin(F &u, const _S &v){
bool flag = false;
if ( u > v ){
u = v; flag |= true;
}
return flag;
}
template <class F, class _S>
bool chmax(F &u, const _S &v){
bool flag = false;
if ( u < v ){
u = v; flag |= true;
}
return flag;
}
void solve(){
int n;
cin >> n;
vector<int> a(n*2+2, 0), b(n*2+2, 0);
for(int i = 1; i <= n*2; i++)cin >> a[i];
for(int i = 1; i <= n*2; i++)cin >> b[i];
pair<int,int> dp[n*2+1][2];
for(int i = 1; i <= n*2; i++){
dp[i][0] = dp[i][1] = {-1,-1};
}
dp[1][0] = {1, 1};
dp[1][1] = {0, 0};
for(int i = 2; i <= n*2; i++){
if(a[i] >= a[i-1] && dp[i-1][0].ff != -1){
if(dp[i][0].ff == -1){
dp[i][0].ff = dp[i-1][0].ff+1;
dp[i][0].ss = dp[i-1][0].ss+1;
}else{
chmin(dp[i][0].ff,dp[i-1][0].ff+1);
chmax(dp[i][0].ss,dp[i-1][0].ss+1);
}
}
if(a[i] >= b[i-1] && dp[i-1][1].ff != -1){
if(dp[i][0].ff == -1){
dp[i][0].ff = dp[i-1][1].ff+1;
dp[i][0].ss = dp[i-1][1].ss+1;
}else{
chmin(dp[i][0].ff,dp[i-1][1].ff+1);
chmax(dp[i][0].ss,dp[i-1][1].ss+1);
}
}
//
if(b[i] >= a[i-1] && dp[i-1][0].ff != -1){
if(dp[i][1].ff == -1){
dp[i][1].ff = dp[i-1][0].ff;
dp[i][1].ss = dp[i-1][0].ss;
}else{
chmin(dp[i][1].ff,dp[i-1][0].ff);
chmax(dp[i][1].ss,dp[i-1][0].ss);
}
}
if(b[i] >= b[i-1] && dp[i-1][1].ff != -1){
if(dp[i][1].ff == -1){
dp[i][1].ff = dp[i-1][1].ff;
dp[i][1].ss = dp[i-1][1].ss;
}else{
chmin(dp[i][1].ff,dp[i-1][1].ff);
chmax(dp[i][1].ss,dp[i-1][1].ss);
}
}
}
//for(int i=1;i<=2*n;i++) {
//cout<<dp[i][0].ff<<' '<<dp[i][0].ss<<" "<<dp[i][1].ff<<' '<<dp[i][1].ss<<endl;
//}
if(dp[n*2][0].ff <= n && dp[n*2][0].ss >= n){
vector<int> ans;
int cur = n, t = 0;
for(int i = n*2; i >= 0; i--){
if(t == 0){cur--;ans.pb(1);}
else ans.pb(0);
if(i == 1)break;
if(t == 0){
if(dp[i-1][0].ff <= cur && dp[i-1][0].ss >= cur && a[i-1] <= a[i]){
t = 0;
}else if(dp[i-1][1].ff <= cur && dp[i-1][1].ss >= cur && b[i-1] <= a[i]){
t = 1;
}
}
else{
if(dp[i-1][0].ff <= cur && dp[i-1][0].ss >= cur && a[i-1] <= b[i]){
t = 0;
}else if(dp[i-1][1].ff <= cur && dp[i-1][1].ss >= cur && b[i-1] <= b[i]){
t = 1;
}
}
}
reverse(all(ans));
for(auto i:ans){
cout << (i==1?"A":"B");
}
}else if(dp[n*2][1].ff <= n && dp[n*2][1].ss >= n){
vector<int> ans;
int cur = n, t = 1;
for(int i = n*2; i >= 0; i--){
if(t == 0){cur--;ans.pb(1);}
else ans.pb(0);
if(i == 1)break;
if(t == 0){
if(dp[i-1][0].ff <= cur && dp[i-1][0].ss >= cur && a[i-1] <= a[i]){
t = 0;
}else if(dp[i-1][1].ff <= cur && dp[i-1][1].ss >= cur && b[i-1] <= a[i]){
t = 1;
}
}
else{
if(dp[i-1][0].ff <= cur && dp[i-1][0].ss >= cur && a[i-1] <= b[i]){
t = 0;
}else if(dp[i-1][1].ff <= cur && dp[i-1][1].ss >= cur && b[i-1] <= b[i]){
t = 1;
}
}
}
reverse(all(ans));
for(auto i:ans){
cout << (i==1?"A":"B");
}
}else{
cout << -1;
}cout << '\n';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int tt = 1;
//cin >> tt;
while(tt--){
solve();
}
}
