#include <algorithm>
#include <bits/stdc++.h>
#include <cassert>
#define ll long long
#define ff first
#define ss second
#define ln "\n"
const ll INF = 2e18;
const ll MOD = 1e9+7;
using namespace std;
void solve(){
ll n; cin >> n; n*=2;
vector<array<ll, 2>> a(n);
for (ll i=0; i<n; i++) cin >> a[i][0];
for (ll i=0; i<n; i++) cin >> a[i][1];
array<ll, 2> inf = {INF, -INF};
vector<array<array<ll, 2>, 2>> dp(n, {inf, inf});
dp[0][0][0] = dp[0][0][1] = 1;
dp[0][1][0] = dp[0][1][1] = -1;
for (ll i=1; i<n; i++){
for (ll j=0; j<2; j++){
if (a[i][j]>=a[i-1][0]){
dp[i][j][0]=min(dp[i][j][0], dp[i-1][0][0]+(j==0?1:-1));
dp[i][j][1]=max(dp[i][j][1], dp[i-1][0][1]+(j==0?1:-1));
}
if (a[i][j]>=a[i-1][1]){
dp[i][j][0]=min(dp[i][j][0], dp[i-1][1][0]+(j==0?1:-1));
dp[i][j][1]=max(dp[i][j][1], dp[i-1][1][1]+(j==0?1:-1));
}
}
}
if ((dp[n-1][0][0]<=0 and dp[n-1][0][1]>=0) or (dp[n-1][1][0]<=0 and dp[n-1][1][1]>=0)){
ll cur=0; string s = "";
ll prev=INF;
for (ll i=n-1; i>=0; i--){
if (dp[i][0][0]<=cur and dp[i][0][1]>=cur and prev>=a[i][0]){
cur--; s+='A'; prev=a[i][0];
}else{
cur++; s+='B'; prev=a[i][1];
}
}
reverse(s.begin(), s.end());
cout << s << ln;
} else {
cout << -1 << ln;
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
ll t=1;
// cin >> t;
while (t--) solve();
}
