#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vi;
typedef pair<ll,ll> pi;
typedef vector<pi> vpi;
typedef long double ld;
#define pb emplace_back
#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define ALL(x) x.begin(), x.end()
#define SZ(x) (ll)x.size()
#define f first
#define s second
const int MAXN = 1000100;
const ll INF = 1e18;
int done[MAXN];
int A[MAXN];
int B[MAXN];
int flip[MAXN];
int N;
vi V;
vi rev;
int cfm[MAXN];
int wgt[MAXN];
int tot;
vi tmp;
int knapflip[MAXN];
void die(){
cout<<-1;
exit(0);
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>N;N*=2;
for (int i=1;i<=N;++i)cin>>A[i];
for (int i=1;i<=N;++i){
cin>>B[i];
if (A[i] > B[i]){swap(A[i], B[i]);flip[i] = 1;}
}
V.pb(0);
for (int i=1;i<=N;++i){
if (A[i] >= V.back())V.pb(A[i]);
else {
if (B[i] < V.back()){
die();
}else{
V.pb(B[i]);
if (flip[i] == 0)done[i] = 2;
else done[i]=1;
}
}
}
rev.pb(INF);
for (int i=N;i>=1;--i){
if (B[i] <= rev.back())rev.pb(B[i]);
else if (A[i] <= rev.back()){
rev.pb(A[i]);
if (done[i]){
die();
}
if (flip[i] == 0)done[i] = 1;
else done[i]=2;
}else{
die();
}
}
int acnt=0;
int bcnt=0;
vi leftovers;
for (int i=1;i<=N;++i){
cfm[i] = 1;
if (done[i] == 0){
leftovers.pb(i);
cfm[i] = 0;
if(flip[i] == 0)done[i] = 1;
else done[i] = 2;
}else{
if (done[i]==1)++acnt;
else ++bcnt;
}
if (done[i] == 1)--tot;
else ++tot;
}
//cout<<tot<<'\n';
if (max(acnt, bcnt) > N/2){
die();
}
vpi store;
//for (auto i:leftovers)cout<<A[i]<<' '<<B[i]<<'\n';
int curind = SZ(leftovers)-1;
int cur = curind;
while (cur){
--cur;
//cout<<leftovers[cur]<<' '<<leftovers[cur+1]<<'\n';
if (B[leftovers[cur]] <= A[leftovers[cur+1]]){
store.pb(cur+1, curind);
curind = cur;
}
}
store.pb(0,curind);
for (auto i : store){
if (tot==0)break;
int a = i.f;
int b = i.s;
//cout<<"Range "<<a<<' '<<b<<'\n';
//cout<<"Total "<<tot<<'\n';
tmp.clear();
tmp.pb(0);
for (int i=b;i>=a;--i){
assert(cfm[leftovers[i]] == 0);
int t = -1;
if (done[leftovers[i]] == 1)t = 2;
else t = -2;
tmp.pb(t + tmp.back());
}
reverse(ALL(tmp));
//for (auto i : tmp)cout<<i<<' ';cout<<'\n';
pi maxele=mp(-INF,INF);
pi minele=mp(INF,INF);
for (int i=0;i<SZ(tmp);++i){
int x = tmp[i];
if (x > maxele.f)maxele=mp(x,i+a);
if(x < minele.f)minele=mp(x,i+a);
if (x+tot == 0){
for (int tt=i+a;tt<=b;++tt)knapflip[leftovers[tt]] = 1;
tot = 0;
break;
}
}
//cout<<tot<<' '<<minele.f<<'\n';
if (tot==0)break;
if (tot < 0){
for (int tt=maxele.s;tt<=b;++tt)knapflip[leftovers[tt]] = 1;
tot += maxele.f;
}else{
for (int tt=minele.s;tt<=b;++tt)knapflip[leftovers[tt]] = 1;
tot += minele.f;
}
}
//cerr<<tot<<'\n';
if (tot !=0){
die();
}
for (int i=1;i<=N;++i)if (knapflip[i])done[i] = 3-done[i];
for (int i=1;i<=N;++i){
if (done[i] == 1){
cout<<'A';
}else{
cout<<'B';
}
}
}
