#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<long long, long long>
#define pb push_back
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
const ll N = 1e6 + 100;
const ll inf = 1e18;
const ll mod = 1e9 + 7;
const ll block = 350;
ll n;
ll a[N][2];
pll dp[N][2];
void to_thic_cau(){
cin >> n;
for(int i = 1; i <= 2 * n;i++) cin >> a[i][0];
for(int i = 1; i <= 2 * n;i++) cin >> a[i][1];
dp[0][0] = dp[0][1] = {0, 0};
for(int i = 1; i <= 2 * n;i++){
dp[i][0] = dp[i][1] = {-1, -1};
for(int j = 0; j <= 1;j++){
if(dp[i-1][j].F != -1){
for(int k = 0; k <= 1;k++){
if(a[i-1][j] <= a[i][k]){
pll cur = dp[i-1][j];
cur.F += k, cur.S += k;
if(dp[i][k].F == -1) dp[i][k] = cur;
else dp[i][k].F = min(dp[i][k].F, cur.F), dp[i][k].S = max(dp[i][k].S, cur.S);
}
}
}
}
}
ll st = -1;
for(int j = 0; j <= 1;j++){
if(dp[2 * n][j].S >= n && dp[2 * n][j].F <= n) st = j;
}
if(st == -1){
cout << -1 << '\n';
return;
}
string ans;
ll cnt = 0;
for(int i = 2 * n; i >= 1;i--){
ans.pb('A' + st);
cnt += st;
for(int j = 0; j <= 1;j++) if(a[i-1][j] <= a[i][st]){
if(dp[i-1][j].F + cnt <= n && dp[i-1][j].S + cnt >= n){
st = j;
break;
}
}
}
reverse(all(ans));
cout << ans << '\n';
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
ll tc = 1;
//cin >> tc;
while(tc--) to_thic_cau();
}
