/*
/^--^\
\____/
/ \ _____ _ __ __ ____ _ ____ ____ _____
| || ()_)| |\ \/ /| ===|| |__ / (__` / () \|_ _|
\__ __/ |_| |_|/_/\_\|____||____|\____)/__/\__\ |_|
|^|^\ \^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|
| | |\ \| | | | | | | | | | | | | | | | | | | | | | | | |
#####/ /#################################################
| | |\/ | | | | | | | | | | | | | | | | | | | | | | | | |
|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|*/
//#pragma GCC optimize("O4,unroll-loops,no-stack-protector")
#include <bits/stdc++.h>
#define int ll //__int128
#define double long double
using namespace std;
using ll=long long;
using ull=unsigned long long;
using pii=pair<int,int>;
#define For(i,a,b) for(int i=a;i<=b;i++)
#define Fors(i,a,b,s) for(int i=a;i<=b;i+=s)
#define Forr(i,a,b) for(int i=a;i>=b;i--)
#define F first
#define S second
#define L(id) (id*2+1)
#define R(id) (id*2+2)
#define LO(x) (x&(-x))
#define eb emplace_back
#define all(x) x.begin(),x.end()
#define sz(x) ((int)x.size())
#define mkp make_pair
#define MOD (int)(1000000007)
#define INF (int)(1e12)
#define EPS (1e-7)
#ifdef NYAOWO
#define debug(...) do{\
cerr << __LINE__ <<\
" : ("#__VA_ARGS__ << ") = ";\
_OUT(__VA_ARGS__);\
cerr << flush;\
}while(0)
template<typename T> void _OUT(T x) { cerr << x << "\n"; }
template<typename T,typename...I>
void _OUT(T x,I ...tail) { cerr << x << ", "; _OUT(tail...); }
#else
#define debug(...)
#endif
inline void NYA(){ ios::sync_with_stdio(false); cin.tie(0); }
inline void USACO(const string &s){
freopen((s+".in").c_str(),"r",stdin);
freopen((s+".out").c_str(),"w",stdout);
}
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
//int gcd(int a,int b) { return b==0?a:gcd(b,a%b); }
inline int gcd(int a,int b) { return __gcd(a,b); }
inline int lcm(int a,int b) { return a/gcd(a,b)*b; }
__int128 fpow(__int128 b,__int128 p,const __int128 &mod){
__int128 ans=1;
while(p){
if(p&1) ans=ans*b%mod;
p/=2; b=b*b%mod;
}
return ans;
}
int fpow(int b,int p) { return fpow(b,p,MOD); }
template<typename T> inline void chmin(T &_a,const T &_b) { if(_b<_a) _a=_b; }
template<typename T> inline void chmax(T &_a,const T &_b) { if(_b>_a) _a=_b; }
#define MAXN 1000010
int a[MAXN];
int b[MAXN];
int la[MAXN];
int ha[MAXN];
int lb[MAXN];
int hb[MAXN];
int32_t main(){
NYA();
//nachoneko so cute >/////<
int n; cin>>n;
For(i,1,n*2) cin>>a[i];
For(i,1,n*2) cin>>b[i];
la[1]=ha[1]=0;
lb[1]=hb[1]=1;
For(i,2,n*2){
la[i]=INF;
ha[i]=-INF;
lb[i]=INF;
hb[i]=-INF;
if(a[i-1]<=a[i]) { chmax(ha[i],ha[i-1]); chmin(la[i],la[i-1]); }
if(b[i-1]<=a[i]) { chmax(ha[i],hb[i-1]); chmin(la[i],lb[i-1]); }
if(a[i-1]<=b[i]) { chmax(hb[i],ha[i-1]); chmin(lb[i],la[i-1]); }
if(b[i-1]<=b[i]) { chmax(hb[i],hb[i-1]); chmin(lb[i],lb[i-1]); }
lb[i]++; hb[i]++;
}
int now=n;
if((now>ha[n*2] || now<la[n*2]) && (now>hb[n*2] || now<lb[n*2])){
cout<<"-1\n";
return 0;
}
//debug(lb[n*2],hb[n*2]);
//debug(la[n*2],ha[n*2]);
//debug(n*2);
string ans;
bool ok=true;
Forr(i,n*2,1){
if(ok && la[i]<=now && now<=ha[i]){
ans+='A';
ok=(a[i-1]<=a[i]);
}else{
ans+='B'; now--;
ok=(a[i-1]<=b[i]);
}
}
reverse(all(ans));
cout<<ans<<"\n"<<flush;
//debug(now);
return 0;
}
