#include <bits/stdc++.h>
#define pb push_back
using namespace std;
#define N 4050
int n;
char t[2]={'A','B'};
int dp[N][N][2], v[2][N], prox[N][N][2];
void print(int i, int qb, int flag,string &s){
if(i>n)return;
int c= prox[i][qb][flag];
s.pb(t[c]);
print(i+1,qb-c,c,s);
}
int solve(int i, int qb, int flag){
if(qb < 0) return 0;
if(i > n) return (qb == 0);
if(dp[i][qb][flag]!=-1)return dp[i][qb][flag];
int ans=0;
for(int c=0;c<2;c++)
if(v[c][i]>=v[flag][i-1] and solve(i+1,qb-c,c)) ans = 1,prox[i][qb][flag]=c;
return dp[i][qb][flag]=ans;
}
int main(){
ios::sync_with_stdio(false); cin.tie(0);
cin>>n;
if(n>3000)return 0;
n *= 2;
for(int i = 1; i <= n; i++) cin>>v[0][i];
for(int i = 1; i <= n; i++) cin>>v[1][i];
memset(dp,-1,sizeof dp);
string s;
int r=-1,l=-1;
for(int c = 1; c <= n; c++){
if(solve(1,c,0)){
r=c;
if(l ==-1)l=c;
}
}
for(int c=l;c<=r and l != -1 and r != -1;c++){
assert(solve(1, c, 0) == 1);
}
if(solve(1,n/2,0))print(1,n/2,0,s),cout<<s<<"\n";
else cout<<"-1\n";
// cout<<solve(1,0,0)<<"\n";
}
