#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define bruh ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fu(x,a,b) for (auto x=a;x<=b;x++)
#define fd(x,a,b) for (auto x=a;x>=b;x--)
#define int ll
using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
/*
Competitive Programming notes that I need to study & fix my dumbass self:
1. Coding:
- Always be sure to check the memory of arrays (maybe use vectors), for loops
- Always try to maximize the memory if possible, even if you are going for subtasks
- Do not exploit #define int long long, it will kill you
2. Stress:
- Always try generating big testcases and try if they run
3. Time management:
- Don't overcommit or undercommit, always spend a certain amount of time to think a problem, don't just look at it and say I'm fucked
- Do not spend too much time coding brute-force solutions, they should be easily-codable solutions that don't take up too much time
Time management schedule:
Offline / LAH days (4 problems - 3h):
15' thinking of solution / idea
1. no idea: skip
2. yes idea: continue thinking for <= 15'
+ implementing: <= 20'
+ brute-force: <= 5'
+ test generator: <= 5'
I hate offline because I am dumb
*/
typedef pair<int, int> ii;
const int N = 1e6+5;
const int B = 750;
const int mod = 1e9+7;
const int inf = 1e18;
using cd = complex<double>;
const long double PI = acos(-1);
int power(int a,int b) {ll x = 1;if (a >= mod) a%=mod; while (b) {if (b & 1) x = x*a % mod;a = a*a % mod;b>>=1;}return x;}
int n;
int a[N], b[N];
ii dp[N][2];
void solve()
{
cin>>n;
for (int i = 1; i <= 2*n; i++) cin>>a[i];
for (int i = 1; i <= 2*n; i++) cin>>b[i];
dp[1][0] = {1,1}, dp[1][1] = {0,0};
for (int i = 2; i <= 2*n; i++)
{
dp[i][0] = dp[i][1] = {inf, -inf};
if (a[i] >= a[i-1]) dp[i][0].fi = min(dp[i][0].fi, dp[i-1][0].fi+1), dp[i][0].se = max(dp[i][0].se, dp[i-1][0].se+1);
if (a[i] >= b[i-1]) dp[i][0].fi = min(dp[i][0].fi, dp[i-1][1].fi+1), dp[i][0].se = max(dp[i][0].se, dp[i-1][1].se+1);
if (b[i] >= a[i-1]) dp[i][1].fi = min(dp[i][1].fi, dp[i-1][0].fi), dp[i][1].se = max(dp[i][1].se, dp[i-1][0].se);
if (b[i] >= b[i-1]) dp[i][1].fi = min(dp[i][1].fi, dp[i-1][1].fi), dp[i][1].se = max(dp[i][1].se, dp[i-1][1].se);
}
// cout<<dp[2*n][0].fi<<" "<<dp[2*n][0].se<<endl;
int cur = 0;
if (dp[2*n][0].fi <= n && n <= dp[2*n][0].se) cur = 0;
else if (dp[2*n][1].fi <= n && n <= dp[2*n][1].se) cur = 1;
else
{
cout<<-1; return;
}
string ans = "";
int cnt = n;
for (int i = 2*n; i >= 1; i--)
{
if (cur == 0)
{
cnt--;
ans += 'A';
if (a[i] >= a[i-1] && (dp[i-1][0].fi <= cnt && cnt <= dp[i-1][0].se)) cur = 0;
else cur = 1;
}
else
{
ans += 'B';
if (b[i] >= a[i-1] && (dp[i-1][0].fi <= cnt && cnt <= dp[i-1][0].se)) cur = 0;
else cur = 1;
}
}
reverse(all(ans));
cout<<ans;
}
/*
Go through the mistakes you usually make and revise your code, for god's sake...
*/
signed main()
{
bruh
//freopen("input.inp","r",stdin);
//freopen("output.inp","w",stdout);
int t = 1;
// cin>>t;
while (t--)
{
solve();
cout<<"\n";
}
}
