#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
#define FOR(i, x, y) for(ll i=x; i<y; i++)
#define FORNEG(i, x, y) for(ll i=x; i>y; i--)
#define fast() ios_base::sync_with_stdio(false);cin.tie(NULL)
pair<ll,ll> dp[1000001][2];
ll a[1000001];
ll b[1000001];
vector<ll> edges[2000001];
ll n;
// dp[i][j] means the number of type 0 buildings we can have when we are at the ith city, and j is
// the type of building we are at when we are at the ith city.
int main(){
cin >> n;
FOR(i,1,2*n+1){
cin >> a[i];
}
FOR(i,1,2*n+1){
cin >> b[i];
}
FOR(i,0,2*n+1){
dp[i][0] = {1000000000,-1000000000};
dp[i][1] = {1000000000,-1000000000};
}
dp[0][0] = dp[0][1] = {0, 0};
FOR(i,1,2*n+1){
if (a[i] >= a[i-1]){
dp[i][0].first = min(dp[i][0].first, dp[i-1][0].first);
dp[i][0].second = max(dp[i][0].second, dp[i-1][0].second);
}
if (a[i] >= b[i-1]){
dp[i][0].first = min(dp[i][0].first, dp[i-1][1].first);
dp[i][0].second = max(dp[i][0].second, dp[i-1][1].second);
}
if (b[i] >= b[i-1]){
dp[i][1].first = min(dp[i][1].first, dp[i-1][1].first);
dp[i][1].second = max(dp[i][1].second, dp[i-1][1].second);
}
if (b[i] >= a[i-1]){
dp[i][1].first = min(dp[i][1].first, dp[i-1][0].first);
dp[i][1].second = max(dp[i][1].second, dp[i-1][0].second);
}
dp[i][0].first++;
dp[i][0].second++;
}
// FOR(i,0,2*n+1){
// cout << dp[i][0].first << " " << dp[i][0].second << endl;
// }
string ans = "";
ll cur = 1000000000;
FORNEG(i,2*n, 0){
if (a[i] > cur || dp[i][0].first > n || dp[i][0].second < n){
if (b[i] > cur || dp[i][1].first > n || dp[i][1].second < n){
cout << -1;
return 0;
}
ans += "B", cur = b[i];
}else ans += "A", cur = a[i],n-=1;
}
reverse(ans.begin(), ans.end());
cout << ans;
}
