#include<bits/stdc++.h>
using ll = long long;
using namespace std;
#define pll pair <ll,ll>
#define fi first
#define se second
#define MP make_pair
#define sz(a) (ll((a).size()))
#define BIT(mask,i) (((mask) >> (i))&1)
#define MASK(i) (1LL << (i))
const ll MAXN = 5e5+100;
ll A[MAXN][2];
bool ans[MAXN];
ll n;
int main(){
ios_base::sync_with_stdio(0);cin.tie(nullptr);
cin>>n;
n*=2;
for (ll i = 1;i <= n;i ++)cin>>A[i][0];
for (ll i = 1;i <= n;i ++)cin>>A[i][1];
ll last = -1;
for (ll i = 1;i <= n;i ++){
bool sw = 0;
if (A[i][0] > A[i][1]){
swap(A[i][0],A[i][1]);
sw = 1;
}
if (max(A[i][0],A[i][1]) < last){
cout<<-1<<endl;
return 0;
}
if (A[i][0] >= last){
ans[i] = 0;
last = A[i][0];
}
else {
ans[i] = 1;
last = A[i][1];
}
if (sw){
swap(A[i][0],A[i][1]);
ans[i] = 1-ans[i];
}
}
ll sum = 0;
for (ll i = 1;i <= n;i ++)sum += ans[i] ? -1 : +1;
last = -1;
auto solve = [&](ll l,ll r){
ll cur = sum;
ll res = abs(sum);
ll res_id = r+1;
for (ll j = r;j >= l;j --){
cur += ans[j] ? +2 : -2;
if (abs(cur) < res){
res = abs(cur);
res_id = j;
}
}
sum = res;
for (ll j = res_id;j <= r;j ++)ans[j] = 1-ans[j];
};
for (ll i = n;i >= 1;i --){
if (A[i][ans[i]] > A[i][1-ans[i]]){
if (last != -1)solve(i+1,last);
last = -1;
}
else{
if (i == n || A[i][1-ans[i]] <= A[i+1][ans[i+1]]){
if (last != -1)solve(i+1,last);
last = i;
}
else{
if (A[i][1-ans[i]] <= A[i+1][1-ans[i+1]]){
}
else{
if (last != -1)solve(i+1,last);
last = -1;
}
}
}
}
if (last != -1)solve(1,last);
if (sum != 0)cout<<-1<<endl;
else for (ll i = 1;i <= n; i++)cout<<char('A' + ans[i]);
}
