#pragma GCC optimization "O2"
#pragma GCC optimization "unroll-loop"
#pragma GCC target ("avx2")
#include <bits/stdc++.h>
#define ll int
#define ld long double
#define fs first
#define sc second
using namespace std;
const ll N = 1e6 + 6;
const ll Log2 = 19;
const ll inf = 1e9 + 7;
typedef pair<ll,ll> LL;
///Road to EF/M
LL dp[N][2];
ll n,a[N][2];
LL f(ll i,ll j){
if (i == n) return {0,0};
if (dp[i][j].fs != -1) return dp[i][j];
LL ans = {inf,-inf};
if (a[i][j] <= a[i + 1][0]){
ans.fs = min(ans.fs,f(i + 1,0).fs);
ans.sc = max(ans.sc,f(i + 1,0).sc);
}
if (a[i][j] <= a[i + 1][1]){
ans.fs = min(ans.fs,f(i + 1,1).fs + 1);
ans.sc = max(ans.sc,f(i + 1,1).sc + 1);
}
return dp[i][j] = ans;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
#define task "tst"
if (fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
//freopen(task".out", "w", stdout);
}
cin>>n; n *= 2;
for (ll i = 0;i <= n;i++) dp[i][0] = dp[i][1] = {-1,-1};
for (ll i = 1;i <= n;i++) cin>>a[i][0];
for (ll i = 1;i <= n;i++) cin>>a[i][1];
//cout<<f(0,0).fs<<" "<<f(0,0).sc; return 0;
if (f(0,0).fs > n/2 || f(0,0).sc < n/2) return cout<<-1,0;
ll prv = 0,rm = n/2;
for (ll i = 1;i <= n;i++){
if (a[i][0] >= a[i - 1][prv]&&f(i,0).fs <= rm&&f(i,0).sc >= rm)
prv = 0,cout<<"A";
else{
prv = 1; cout<<"B"; rm--;
}
}
}
