#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[1000005],b[1000005],c[1000005];
string ans,res;
//vector<int> free;
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(ans[id+1]!=' ')
{
if(c[id]>c[id+1])
{
cout<<-1;
exit(0);
}
return;
}
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+' ';
res=res+' ';
}
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);
gorig(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';
}
golef(i+1);
gorig(i+1);
}
}
// cout<<'?'<<ans<<endl;
// for(int i=1;i<=n;i++)
// {
// if()
// }
int cnt=0;
for(int i=1;i<=n;i++)
{
if(ans[i]=='A') cnt++;
else
if(ans[i]=='B') cnt--;
// else
if(ans[i]==' ')
{
if(a[i]<b[i])
{
res[i]='B';
cnt--;
}
else
if(b[i]<a[i])
{
res[i]='A';
cnt++;
}
else
{
// res[i]=' ';
// cout<<i<<endl;
cnt--;
}
}
}
// cout<<'?'<<res<<endl;
for(int i=1;i<=n;i++)
{
// cout<<i<<endl;
if(ans[i]==' '&&res[i]!=' ')
{
int mx=0,mn=0,sum=0,nexi=i;
for(int j=i;j<=n;j++)
{
// if(j!=1&&max(a[j-1],b[j-1])<=min(a[j],b[j])) break;
if(res[j]==' ') break;
if(res[j]=='A') sum-=2;
else sum+=2;
mx=max(mx,sum);
mn=min(mn,sum);
nexi=j;
if(j!=n&&max(a[j],b[j])<=min(a[j+1],b[j+1])) break;
}
if(cnt<0)
{
if(cnt+mx>0)
{
mx=0-cnt;
cnt=0;
}
else cnt+=mx;
int sum=0;
bool ok=false;
for(int j=i;j<=nexi;j++)
{
if(sum==mx) ok=true;
if(!ok)
{
if(res[j]=='A') ans[j]='B';
else ans[j]='A';
}
else ans[j]=res[j];
if(res[j]=='A') sum-=2;
else sum+=2;
}
}
else
{
if(cnt+mn<0)
{
mn=0-cnt;
cnt=0;
}
else cnt+=mn;
int sum=0;
bool ok=false;
for(int j=i;j<=nexi;j++)
{
if(sum==mn) ok=true;
if(!ok)
{
if(res[j]=='A') ans[j]='B';
else ans[j]='A';
}
else ans[j]=res[j];
if(res[j]=='A') sum-=2;
else sum+=2;
}
}
i=nexi;
}
}
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<<-1;
else
cout<<ans;
}
/*
em thi cho du co khoc
cung se den ngay phai quen
thien duong van cho ngay em den
*/
