#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define MOD 1000000007
typedef long long ll;
typedef pair <int, int> ii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef long double ld;
ll INF=LLONG_MAX;
int const mxn = 1e6+5;
int dp[mxn][2][2]; //pos, cur, last
int a[mxn],b[mxn];
void maxs(int &a, int b){
a=max(a,b);
return;
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
//freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
int n; cin >> n;
memset(dp,-1,sizeof(dp));
for(int i=1; i<=n*2; i++)cin >> a[i];
for(int i=1; i<=n*2; i++)cin >> b[i];
dp[1][0][0] = 0;
dp[1][1][0] = 1;
for(int i=1; i<n*2; i++){
for(int j=0; j<2; j++){
for(int k=0; k<2; k++){
if(dp[i][j][k]!=-5){
if(!j){//now is A
if(a[i]<=a[i+1])maxs(dp[i+1][0][0],dp[i][j][k]);
if(a[i]<=b[i+1])maxs(dp[i+1][1][0],dp[i][j][k]+1);
}else{//now is b
if(b[i]<=a[i+1])maxs(dp[i+1][0][1],dp[i][j][k]);
if(b[i]<=b[i+1])maxs(dp[i+1][1][1],dp[i][j][k]+1);
}
}
}
}
}
bool find=0,cur=0,last=0;
for(int i=0; i<2&&!find; i++){
for(int j=0; j<2&&!find; j++){
if(dp[n*2][i][j]>=n){
cur = i;
last = j;
find = 1;
}
}
}
if(!find){
cout << -1 << endl;
return 0;
}
//start backtracking
string s="";
int ptr = 2*n, cnt = n;
while(ptr!=0){
bool aa=0,bb=0;
if(!cur){
s+="A";
}else{
s+="B";
cnt--;
if(cnt<0){
cout << -1 << endl;
return 0;
}
}
if(dp[ptr-1][last][0] >= cnt)aa=1;
if(dp[ptr-1][last][1] >= cnt)bb=1;
if(aa&&bb){
if(dp[ptr-1][last][0]<=dp[ptr-1][last][1]){
cur = last;
last = 0;
}else{
cur = last;
last = 1;
}
}else if(aa){
cur = last;
last = 0;
}else if(bb){
cur = last;
last = 1;
}else if(ptr>1){
cout << -1 << endl;
return 0;
}
ptr--;
}
reverse(all(s));
cout << s << endl;
}
