#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast,unroll-loops")
#define ll long long
#define int ll
#define ull unsigned ll
#define ld long double
#define rep(a) rep1(i,a)
#define rep1(i,a) rep2(i,0,a)
#define rep2(i,b,a) for(int i=(b); i<((int)(a)); i++)
#define rep3(i,b,a) for(int i=(b); i>=((int)(a)); i--)
#define chkmin(a,b) (a=min(a,b))
#define chkmax(a,b) (a=max(a,b))
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define pb push_back
//#define inf 1010000000
#define inf 4000000000000000000
#define eps 1e-9
#define sz(a) ((int)a.size())
#define pow2(x) (1ll<<(x))
#define ceiling(a,b) (((a)+(b)-1)/(b))
#define print0(a) cout << (a) << ' '
#define ykh mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#ifdef i_am_noob
#define bug(...) cerr << "#" << __LINE__ << ' ' << #__VA_ARGS__ << "- ", _do(__VA_ARGS__)
template<typename T> void _do(T && x) {cerr << x << endl;}
template<typename T, typename ...S> void _do(T && x, S&&...y) {cerr << x << ", "; _do(y...);}
#else
#define bug(...) 777771449
#endif
const int mod=1000000007;
const int maxn=1000005,maxm=18,maxk=7777714;
//i_am_noob
int n,a[maxn],b[maxn],dp[maxn][2][2];
bool res[maxn];
void orzck(){
cin >> n;
n*=2;
rep(n) cin >> a[i];
rep(n) cin >> b[i];
rep(2) rep1(j,2) dp[0][i][j]=i^1;
rep2(i,1,n){
rep1(j,2) dp[i][j][0]=inf,dp[i][j][1]=-inf;
if(a[i]>=a[i-1]) chkmin(dp[i][0][0],dp[i-1][0][0]+1),chkmax(dp[i][0][1],dp[i-1][0][1]+1);
if(a[i]>=b[i-1]) chkmin(dp[i][0][0],dp[i-1][1][0]+1),chkmax(dp[i][0][1],dp[i-1][1][1]+1);
if(b[i]>=a[i-1]) chkmin(dp[i][1][0],dp[i-1][0][0]),chkmax(dp[i][1][1],dp[i-1][0][1]);
if(b[i]>=b[i-1]) chkmin(dp[i][1][0],dp[i-1][1][0]),chkmax(dp[i][1][1],dp[i-1][1][1]);
}
rep(2) rep1(j,2) bug(i,j,dp[n-1][i][j]);
int de,tar=n/2,val=inf;
rep3(i,n-1,0){
de=-1;
rep1(_,2){
if(dp[i][_][0]<=tar&&dp[i][_][1]>=tar&&(_?b[i]:a[i])<=val){
de=_,val=(_?b[i]:a[i]);
break;
}
}
bug(de);
if(de==-1){
cout << "-1\n";
return;
}
res[i]=de;
tar-=de^1;
}
rep(n) cout << (res[i]?'B':'A');
cout << "\n";
}
signed main(){
ios_base::sync_with_stdio(0),cin.tie(0);
orzck();
return 0;
}
