#include<bits/stdc++.h>
using namespace std;
const int N = 5e5;
const int inf = 2e9;
int v[2*N][2];
pair<int,int> dp[2*N][2];
bool ans[2*N];
int main(){
int n;
cin>>n;
for(int i = 0;i < 2*n;i++){
cin>>v[i][0];
}
for(int i = 0;i < 2*n;i++){
cin>>v[i][1];
}
for(int i = 2*n - 1;i >= 0;i--){
dp[i][0] = {inf,-inf};
dp[i][1] = {inf,-inf};
if(i == 2*n - 1){
dp[i][0] = {0,0};
dp[i][1] = {1,1};
}else{
for(int j = 0;j < 2;j++){
for(int k = 0;k < 2;k++){
if(v[i][j] <= v[i + 1][k]){
dp[i][j].first = min(dp[i][j].first,dp[i + 1][k].first + j);
dp[i][j].second = max(dp[i][j].second,dp[i + 1][k].second + j);
}
}
}
}
//cout<<dp[i][0].first<<' '<<dp[i][0].second<<' '<<dp[i][1].first<<' '<<dp[i][1].second<<'\n';
}
int target = n;
int prv = -1;
if(dp[0][0].first <= target && target <= dp[0][0].second)prv = 0;
if(dp[0][1].first <= target && target <= dp[0][1].second)prv = 1;
if(prv == -1){
cout<<-1;
}else{
ans[0] = prv;
target-=prv;
for(int i = 1;i < 2*n;i++){
int cur = -1;
if(dp[i][0].first <= target && target <= dp[i][0].second && v[i - 1][prv] <= v[i][0])cur = 0;
if(dp[i][1].first <= target && target <= dp[i][1].second && v[i - 1][prv] <= v[i][1])cur = 1;
ans[i] = cur;
target-=cur;
prv = cur;
}
for(int i = 0;i < 2*n;i++){
cout<<(ans[i] == 1?'B':'A');
}
}
return 0;
}
/**
2
39 69 61 90
63 58 71 78
**/
