#include <bits/stdc++.h>
#define pb push_back
#define ll long long
#define s second
#define f first
using namespace std;
const int N = 1000005;
int a[N],b[N];
pair<int,int> dp[4][N];
main (){
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int n;
cin>>n;
for (int i=1;i<=2*n;i++) cin>>a[i];
for (int i=1;i<=2*n;i++){
cin>>b[i];
dp[1][i] = {2e9,0};
dp[2][i] = {2e9,0};
}
dp[1][1] = {1,1};
dp[2][1] = {0,0};
for (int i=1;i<=2*n;i++){
if (a[i] >= a[i - 1]) dp[1][i] = {min(dp[1][i].f,dp[1][i-1].f + 1),max(dp[1][i].s,dp[1][i-1].s + 1)};
if (a[i] >= b[i - 1]) dp[1][i] = {min(dp[1][i].f,dp[2][i-1].f + 1),max(dp[1][i].s,dp[2][i-1].s + 1)};
if (b[i] >= a[i - 1]) dp[2][i] = {min(dp[2][i].f,dp[1][i-1].f),max(dp[2][i].s,dp[1][i-1].s)};
if (b[i] >= b[i - 1]) dp[2][i] = {min(dp[2][i].f,dp[2][i-1].f),max(dp[2][i].s,dp[2][i-1].s)};
}
int c=0;
if (dp[1][2*n].f <= n && dp[1][2*n].s >= n) c=1;
if (dp[2][2*n].f <= n && dp[2][2*n].s >= n) c=1;
if (!c) {cout<<-1; return 0;}
string s = "";
int cnta = n,l=1e9;
for (int i=2*n;i>=1;i--){
if (a[i] <= l && dp[1][i].f <= cnta && dp[1][i].s >= cnta) cnta--,l=a[i],s+='A';
else l = b[i],s+='B';
}
reverse(s.begin(),s.end());
cout<<s;
}
