#include <bits/stdc++.h>
#define pb push_back
#define ll long long
#define s second
#define f first
using namespace std;
const int N = 500005;
int a[N],b[N],c[N],A,B;
char s[N];
int main (){
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int n;
cin>>n;
n*=2;
for (int i=1;i<=n;i++) cin>>a[i];
for (int i=1;i<=n;i++) cin>>b[i];
int last = 0;
bool check=1;
for (int i=1;i<=n;i++){
if (a[i] >= last && b[i] >= last){
if (a[i] < b[i]) A++,c[i] = a[i],s[i] = 'A';
else B++,c[i] = b[i],s[i] = 'B';
}
else if (a[i] >= last) A++,c[i] = a[i],s[i] = 'A';
else if (b[i] >= last) B++,c[i] = b[i],s[i] = 'B';
else {check=0; break;}
last = c[i];
}
c[n+1]=1e9;
for (int i=n;i>=1;i--){
if (A > B && s[i] == 'B') continue;
if (B > A && s[i] == 'A') continue;
if (A == B) continue;
if (s[i] == 'B') {
if (a[i] >= c[i - 1] && a[i] <= c[i+1])
B--,A++,c[i] = a[i],s[i] = 'A';
}
else {
if (b[i] >= c[i - 1] && b[i] <= c[i+1])
A--,B++,c[i] = b[i],s[i] = 'B';
}
}
if (!check || A!=B) cout<<-1;
else{
for (int i=1;i<=n;i++)
cout<<s[i];
}
}
