#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define ff first
#define ss second
using namespace std;
int n,m,k,i,j,ans,a[2][500005],d[2][500005][2];
int main() {
cin>>n;
n*=2;
for(k=1; k<=n; k++)
cin>>a[1][k];
for(k=1; k<=n; k++)
cin>>a[0][k];
for(k=1; k<=n; k++){
for(i=0; i<=1; i++){
d[i][k][0]=n+1;
d[i][k][1]=-1;
for(j=0; j<=1; j++){
if(a[j][k-1]<=a[i][k]){
d[i][k][0]=min(d[i][k][0],d[j][k-1][0]+i);
d[i][k][1]=max(d[i][k][1],d[j][k-1][1]+i);
}
}
}
}
int sz=-1;
int pos=-1;
if(d[0][n][0]<=n/2 && d[0][n][1]>=n/2){
sz=n;
pos=0;
}
if(d[1][n][0]<=n/2 && d[1][n][1]>=n/2){
sz=n;
pos=1;
}
string s(n,' ');
if(sz==-1){
cout<<-1;
return 0;
}
int cnt;
cnt=n/2;
while(sz--){
if(pos==0){
s[sz]='B';
}
else s[sz]='A';
cnt-=pos;
if(a[pos][sz+1]>=a[1][sz] && d[1][sz][0]<=cnt && d[1][sz][1]>=cnt){
pos=1;
}
else pos=0;
}
cout<<s;
}
