#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define INF (int)1e18
#define all(v) v.begin(), v.end()
const int MAXN =1e6+7;
int n;
int dp[MAXN][2][2]; // min and max A if ith bit=j
int ara[2][MAXN];
void min_self(int &x,int y){
x=min(x,y);
}
void max_self(int &x,int y){
x=max(x,y);
}
int32_t main(){
ios_base::sync_with_stdio(false),cin.tie(),cout.tie();
// If you hack my code, you are gay
cin>>n;
int N=2*n;
for(auto x:{0,1}){
for(int i=0;i<N;i++){
cin>>ara[x][i];
dp[i][x][0]=INF;
dp[i][x][1]=0;
}
}
ara[0][N]=INF;
dp[0][0][0]=dp[0][0][1]=1;
dp[0][1][0]=dp[0][1][1]=0;
for(int i=1;i<N;i++){
for(auto x:{0,1}){
if(ara[x][i-1]<=ara[0][i]){
min_self(dp[i][0][0],dp[i-1][x][0]+1);
max_self(dp[i][0][1],dp[i-1][x][1]+1);
}
if(ara[x][i-1]<=ara[1][i]){
min_self(dp[i][1][0],dp[i-1][x][0]);
max_self(dp[i][1][1],dp[i-1][x][1]);
}
}
}
string ans;
int rem=n;
int last=0;
for(int i=N-1;i>=0;i--){
char ch='A';
if(dp[i][0][0]<=rem && rem<=dp[i][0][1] && ara[0][i]<=ara[last][i+1]){
rem--;
last=0;
}else if(dp[i][1][0]<=rem && rem<=dp[i][1][1] && ara[1][i]<=ara[last][i+1]){
last=1;
ch='B';
}else{
cout<<-1;
return 0;
}
ans.push_back(ch);
}
reverse(all(ans));
cout<<ans;
return 0;
}
