#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define ins insert
#define pb push_back
#define foru(i,a,b) for(int i=a;i<=b;i++)
#define ford(i,a,b) for(int i=a;i>=b;i--)
#define pii pair<int,int>
#define pll pair<ll,ll>
//#define int ll
using namespace std;
int n,a[500005],b[500005],c[500005];
string ans;
void golef(int id)
{
if(id==1||max(a[id-1],b[id-1])<=c[id]) return;
else
{
if(ans[id-1]!=' ')
{
if(c[id-1]>c[id])
{
cout<<-1;
exit(0);
}
return;
}
if(a[id-1]<b[id-1])
{
c[id-1]=a[id-1];
ans[id-1]='A';
}
else
{
c[id-1]=b[id-1];
ans[id-1]='B';
}
golef(id-1);
}
}
void gorig(int id)
{
if(id==n||c[id]<=min(a[id+1],b[id+1])) return;
else
{
if(c[id]>max(a[id+1],b[id+1]))
{
cout<<-1;
exit(0);
}
if(a[id+1]<b[id+1])
{
c[id+1]=b[id+1];
ans[id+1]='B';
}
else
{
c[id+1]=a[id+1];
ans[id+1]='A';
}
gorig(id+1);
}
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
// freopen(".inp","r",stdin);
// freopen(".out","w",stdout);
cin>>n;
n*=2;
for(int i=0;i<=n+1;i++)
{
ans=ans+' ';
}
for(int i=1;i<=n;i++) cin>>a[i];
for(int i=1;i<=n;i++) cin>>b[i];
for(int i=1;i<=n-1;i++)
{
if(ans[i]!=' ') continue;
if(min(a[i],b[i])>max(a[i+1],b[i+1]))
{
cout<<-1;
return 0;
}
if(max(a[i],b[i])>max(a[i+1],b[i+1]))
{
if(a[i]>b[i])
{
c[i]=b[i];
ans[i]='B';
}
else
{
c[i]=a[i];
ans[i]='A';
}
golef(i);
}
if(min(a[i],b[i])>min(a[i+1],b[i+1]))
{
if(a[i+1]>b[i+1])
{
c[i+1]=a[i+1];
ans[i+1]='A';
}
else
{
c[i+1]=b[i+1];
ans[i+1]='B';
}
gorig(i);
}
}
// cout<<'?'<<ans<<endl;
int cnt=0;
for(int i=1;i<=n;i++)
{
if(ans[i]=='A') cnt++;
else cnt--;
}
for(int i=1;i<=n;i++)
{
if(ans[i]==' ')
{
if(cnt<0)
{
cnt+=2;
ans[i]='A';
}
else ans[i]='B';
}
}
ans.erase(ans.begin(),ans.begin()+1);
if(cnt==0) cout<<ans;
else cout<<-1;
}
/*
em thi cho du co khoc
cung se den ngay phai quen
thien duong van cho ngay em den
*/
