#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<int,int>pii;
typedef pair<pii,pii>pi2;
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
int n;
int a[1000005];
int b[1000005];
int memo[4005][2005][2];
array<int,3>pp[4005][4005][2];
//a is true, b is false
int dp(int index, int take, bool amos){
if(index==2*n){
if(take==n){
return true;
}
else return false;
}
if(memo[index][take][amos]!=-1) return memo[index][take][amos];
bool ans=false;
if(index==0){
bool hold=dp(index+1,take+1,true);
if(hold) pp[index][take][amos]={index+1,take+1,true};
ans|=hold;
hold=dp(index+1,take,false);
if(hold) pp[index][take][amos]={index+1,take,false};
ans|=hold;
}
else if(amos){
if(a[index]>=a[index-1]){
//ans|=dp(index+1,take+1,true);
bool hold=dp(index+1,take+1,true);
if(hold) pp[index][take][amos]={index+1,take+1,true};
ans|=hold;
}
if(b[index]>=a[index-1]){
//ans|=dp(index+1,take,false);
bool hold=dp(index+1,take,false);
if(hold) pp[index][take][amos]={index+1,take,false};
ans|=hold;
}
}
else{
if(a[index]>=b[index-1]){
//ans|=dp(index+1,take+1,true);
bool hold=dp(index+1,take+1,true);
if(hold) pp[index][take][amos]={index+1,take+1,true};
ans|=hold;
}
if(b[index]>=b[index-1]){
//ans|=dp(index+1,take,false);
bool hold=dp(index+1,take,false);
if(hold) pp[index][take][amos]={index+1,take,false};
ans|=hold;
}
}
return memo[index][take][amos]=(int)ans;
}
void solve(){
cin >> n;
for(int x=0;x<2*n;x++){
cin >> a[x];
}
for(int x=0;x<2*n;x++){
cin >> b[x];
}
memset(memo,-1,sizeof(memo));
bool hold=dp(0,0,0);
if(!hold){
cout << -1;
return;
}
array<int,3>cur;
cur={0,0,0};
while(cur[0]<2*n){
array<int,3>nxt=pp[cur[0]][cur[1]][cur[2]];
if(nxt[2]==1){
cout << "A";
}
else cout << "B";
cur=nxt;
}
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
//cin >> t;
while(t--){
solve();
}
}
