/*input
3
2 5 4 9 15 11
6 7 6 8 12 14
*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define int long long
#define double long double
#define f first
#define s second
#define mp make_pair
#define pb push_back
#define RE(i,n) for (int i = 1; i <= n; i++)
#define RED(i,n) for (int i = n; i > 0; i--)
#define REPS(i,n) for(int i = 1; (i*i) <= n; i++)
#define REP(i,n) for (int i = 0; i < (int)n; i++)
#define FOR(i,a,b) for (int i = a; i < b; i++)
#define REPD(i,n) for (int i = n-1; i >= 0; i--)
#define FORD(i,a,b) for (int i = a; i >= b; i--)
#define all(v) v.begin(),v.end()
#define pii pair<int,int>
#define vi vector<int>
#define vvi vector<vi>
#define print(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout << *it << " "; cout << endl;
#define debug(x) cout << x << endl;
#define debug2(x,y) cout << x << " " << y << endl;
#define debug3(x,y,z) cout << x << " " << y << " " << z << endl;
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
const int INF = 1e18+1;
const int MOD = 1e9+7;
const double PI = 3.14159265358979323846264338;
int raise(int a,int n,int m = MOD){
if(n == 0)return 1;
if(n == 1)return a;
int x = 1;
x *= raise(a,n/2,m);
x %= m;
x *= x;
x %= m;
if(n%2)x*= a;
x %= m;
return x;
}
int floor1(int n,int k){
if(n%k == 0 || n >= 0)return n/k;
return (n/k)-1;
}
int ceil1(int n,int k){
return floor1(n+k-1,k);
}
const int N = 5e5+1;
int n;
int a[2*N];
int b[2*N];
pair<int,int> fa[2*N];
pair<int,int> fb[2*N];
void solve(){
cin >> n;
RE(i,2*n){
cin >> a[i];
}
RE(i,2*n){
cin >> b[i];
}
fa[1] = {0,0};
fb[1] = {1,1};
for(int i = 2;i <= 2*n;i++){
fa[i] = {INF,-INF};
fb[i] = {INF,-INF};
if(fb[i-1].f != INF and a[i] >= b[i-1]){
fa[i].f = min(fb[i-1].f,fa[i].f);
fa[i].s = max(fb[i-1].s,fa[i].s);
}
if(fa[i-1].f != INF and a[i] >= a[i-1]){
fa[i].f = min(fa[i-1].f,fa[i].f);
fa[i].s = max(fa[i-1].s,fa[i].s);
}
if(fb[i-1].f != INF and b[i] >= b[i-1]){
fb[i].f = min(fb[i-1].f+1,fb[i].f);
fb[i].s = max(fb[i-1].s+1,fb[i].s);
}
if(fa[i-1].f != INF and b[i] >= a[i-1]){
fb[i].f = min(fa[i-1].f+1,fb[i].f);
fb[i].s = max(fa[i-1].s+1,fb[i].s);
}
/*cout << "FOR " << i << endl;
cout << fa[i].f << " " << fa[i].s << endl;
cout << fb[i].f << " " << fb[i].s << endl;*/
}
stack<char> ans;
int cur = 2*n;
int which = 0;
if(fa[2*n].f <= n and n <= fa[2*n].s)which = 1;
if(fb[2*n].f <= n and n <= fb[2*n].s)which = 2;
if(which == 0){
cout << -1;
return;
}
while(cur > 0){
int val;
if(which == 1){
ans.push('A');
val = a[cur];
}
else{
ans.push('B');
n--;
val = b[cur];
}
cur--;
if(a[cur] <= val and fa[cur].f <= n and fa[cur].s >= n){
which = 1;
continue;
}
if(b[cur] <= val and fb[cur].f <= n and fb[cur].s >= n){
which = 2;
continue;
}
}
while(ans.size()){
cout << ans.top();
ans.pop();
}
}
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//freopen(".in","r",stdin);freopen(".out","w",stdout);
int t = 1;
//cin >> t;
while(t--){
solve();
}
return 0;
}
