#include <bits/stdc++.h>
using namespace std;
#define oo 1e15
#define fi first
#define se second
#define sp(iiii) setprecision(iiii)
#define IO ios_base::sync_with_stdio(false); cin.tie(0)
#define ms(aaaa,xxxx) memset(aaaa,xxxx,sizeof(aaaa))
#define cntbit(xxxx) __builtin_popcount(xxxx)
#define getbit(xxxx,aaaa) ((xxxx>>(aaaa-1))&1)
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<pair<int,int>,int> piii;
typedef pair<long long,long long> pll;
typedef pair<pair<long long,long long>,long long> plll;
typedef pair<pair<long long,long long>,pair<long long,long long>> pllll;
typedef pair<pair<long long,long long>,bool> pllb;
const ll base=361;
const ll mod=1e9+7;
const ld eps=1e-5;
const ll maxn=1e7-1;
ll n,i,a[500009],b[500009],f[5009][5009][4],j;
void Trace(ll x,ll y,ll msk) {
if (x==0) {
return;
}
if (msk==1) {
if (f[x-1][y-1][0]&&b[x]>=a[x-1]) {
Trace(x-1,y-1,0);
}
else {
Trace(x-1,y-1,1);
}
cout<<'B';
}
else {
if (f[x-1][y][0]&&a[x]>=a[x-1]) {
Trace(x-1,y,0);
}
else {
Trace(x-1,y,1);
}
cout<<'A';
}
}
int main(){
IO;
cin>>n;
for (i=1;i<=2*n;i++) {
cin>>a[i];
}
for (i=1;i<=2*n;i++) {
cin>>b[i];
}
if (n<=2000) {
f[0][0][1]=true;
f[0][0][0]=true;
for (i=1;i<=2*n;i++) {
for (j=0;j<=n;j++) {
if (a[i]>=a[i-1]) {
f[i][j][0]|=f[i-1][j][0];
}
if (a[i]>=b[i-1]) {
f[i][j][0]|=f[i-1][j][1];
}
if (b[i]>=a[i-1]) {
f[i][j][1]|=f[i-1][j-1][0];
}
if (b[i]>=b[i-1]) {
f[i][j][1]|=f[i-1][j-1][1];
}
}
}
if (f[2*n][n][0]) {
Trace(2*n,n,0);
}
else if (f[2*n][n][1]) {
Trace(2*n,n,1);
}
else {
cout<<-1;
}
}
}
