//#include<i_am_noob_orz>
#include<bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
#define ll long long
#define int ll
#define ull unsigned long long
#define pii pair<int,int>
#define X first
#define Y second
#define mod ((ll)1e9+7)
#define pb push_back
#define mp make_pair
#define abs(x) ((x)>0?(x):(-(x)))
#define F(n) Fi(i,n)
#define Fi(i,n) Fl(i,0,n)
#define Fl(i,l,n) for(int i=l;i<n;i++)
#define memres(a) memset(a,0,sizeof(a))
#define all(a) a.begin(),a.end()
#define sz(a) ((int)a.size())
#define ceiling(a,b) (((a)+(b)-1)/(b))
#define endl '\n'
#define bit_count(x) __builtin_popcountll((x))
#define ykh mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define jimmy_is_kind false
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> rbtree;
#undef LOCAL
//#define LOCAL
#ifdef LOCAL
#define bug(...) cerr<<"#"<<__LINE__<<' '<<#__VA_ARGS__<<"- ", _do(__VA_ARGS__)
template<typename T> void _do(T && x) {cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T && x, S&&...y) {cerr<<x<<", "; _do(y...);}
#define IOS()
#else
#define IOS() ios_base::sync_with_stdio(0), cin.tie(0)
#define endl '\n'
#define bug(...)
#endif
int add(int a,int b){return(a+b>=mod?a+b-mod:a+b);}
int sub(int a,int b){return(a<b?a+mod-b:a-b);}
int po(int a,int b){
if(b==0)return 1;
if(b==1)return(a%mod);
int tem=po(a,b/2);
if(b&1)return(((tem*tem)%mod)*a)%mod;
else return(tem*tem)%mod;
}
int GCD(int a,int b){
int x=0;
int ra,rb;
while(a&&b){
if(((a&1)==0)&&((b&1)==0)){
a>>=1,b>>=1,x++;
}
else if((a^b)&1){
if(a&1)b>>=1;
else a>>=1;
}
else{
ra=abs(a-b),rb=min(a,b);
a=ra,b=rb;
}
}
return max(a,b)<<x;
}
int gcd(int a,int b){if(b==0)return a;return gcd(b,a%b);}
int n,N;
int a[1000010],b[1000010];
bool ttag[1000010];
vector<int> o;
signed main(){
IOS();
cin>>n;
N=n*2;
F(N)cin>>a[i];
F(N)cin>>b[i];
int np=-1e9;
int x=0;
bool tag=0,flag=0;
memres(ttag);
F(N){
if(a[i]<=b[i]){
if(a[i]>=np){
np=a[i];
x++;
o.pb(0);
}
else if(b[i]>=np){
np=b[i];
o.pb(1);
}
else{
tag=1;
break;
}
}
else{
if(b[i]>=np){
np=b[i];
o.pb(1);
}
else if(a[i]>=np){
np=a[i];
x++;
o.pb(0);
}
else{
tag=1;
break;
}
}
}
bug(x);
if(tag){
cout<<"-1"<<endl;
return 0;
}
bug("c");
if(x<n){
x=N-x;
swap(a,b);
F(N)o[i]=1-o[i];
flag=1;
}
vector<int> v,s(N);
for(int i=N-1;i>=0;i--){
if(i==N-1){
v.pb(i);
if(o[i]==0){
if(b[i]>=a[i]){
s[i]=1;
}
else{
s[i]=0;
}
}
else{
if(a[i]>=b[i]){
s[i]=-1;
}
else{
s[i]=0;
}
}
}
else{
if(o[i]==0){
if(b[i]>=a[i]){
if(s[i+1]==1){
if(b[i]<=a[i+1]){
s[i]=1;
v.pb(i);
}
else if(b[i]<=b[i+1]){
s[i]=1;
}
else{
s[i]=0;
v.pb(i);
}
}
else if(s[i+1]==-1){
if(b[i]<=b[i+1]){
s[i]=1;
v.pb(i);
}
else if(b[i]<=a[i+1]){
s[i]=1;
}
else{
s[i]=0;
v.pb(i);
}
}
else{
if(o[i+1]==0){
if(b[i]<=a[i+1]){
s[i]=1;
v.pb(i);
}
else{
s[i]=0;
v.pb(i);
}
}
else{
if(b[i]<=b[i+1]){
s[i]=1;
v.pb(i);
}
else{
s[i]=0;
v.pb(i);
}
}
}
}
else{
s[i]=0;
v.pb(i);
}
}
else{
if(a[i]>=b[i]){
if(s[i+1]==1){
if(a[i]<=a[i+1]){
s[i]=-1;
v.pb(i);
}
else if(a[i]<=b[i+1]){
s[i]=-1;
}
else{
s[i]=0;
v.pb(i);
}
}
else if(s[i+1]==-1){
if(a[i]<=b[i+1]){
s[i]=-1;
v.pb(i);
}
else if(a[i]<=a[i+1]){
s[i]=-1;
}
else{
s[i]=0;
v.pb(i);
}
}
else{
if(o[i+1]==0){
if(a[i]<=a[i+1]){
s[i]=-1;
v.pb(i);
}
else{
s[i]=0;
v.pb(i);
}
}
else{
if(a[i]<=b[i+1]){
s[i]=-1;
v.pb(i);
}
else{
s[i]=0;
v.pb(i);
}
}
}
}
else{
s[i]=0;
v.pb(i);
}
}
}
}
int co=x-n;
bug(sz(v),co);
F(sz(v)){
if(co==0)break;
bug(v[i]);
int l,r;
if(i==sz(v)-1){
l=0,r=v[i];
}
else{
l=v[i+1]+1,r=v[i];
}
int ma=0,mip=-1,no=0;
for(int j=r;j>=l;j--){
no+=s[j];
if(no>ma){
ma=no,mip=j;
}
if(ma==co)break;
}
if(ma>0){
for(int j=mip;j<=r;j++){
if(s[j]!=0){
o[j]=1-o[j];
}
}
}
co-=ma;
if(co==0)break;
}
F(N)bug(s[i]);
//cout<<co<<endl;
if(co!=0){
cout<<"-1"<<endl;
return 0;
}
for(int i:o){
if(flag)i=1-i;
cout<<(i?'B':'A');
}
cout<<endl;
return 0;
}
/*
3
6 7 6 8 12 14
2 5 4 9 15 11
*/
