#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
const int inf=1e9;
int n,a[1000001],b[1000001];
pii dp[1000001][2];
pii merge(pii a, pii b) {return pii(min(a.first,b.first),max(a.second,b.second));}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n;
for (int i=0; i<2*n; ++i) cin>>a[i];
for (int i=0; i<2*n; ++i) cin>>b[i];
dp[0][0]=pii(0,0);
dp[0][1]=pii(1,1);
for (int i=1; i<2*n; ++i) {
dp[i][0]=pii(inf,-inf);
if (a[i]>=a[i-1]) dp[i][0]=merge(dp[i][0],dp[i-1][0]);
if (a[i]>=b[i-1]) dp[i][0]=merge(dp[i][0],dp[i-1][1]);
dp[i][1]=pii(inf,-inf);
if (b[i]>=a[i-1]) dp[i][1]=merge(dp[i][1],dp[i-1][0]);
if (b[i]>=b[i-1]) dp[i][1]=merge(dp[i][1],dp[i-1][1]);
dp[i][1]=pii(dp[i][1].first+1,dp[i][1].second+1);
}
if (dp[2*n-1][0].first<=n && n<=dp[2*n-1][0].second) {
string ans="A";
int cnt=n, last=a[2*n-1];
for (int i=2*n-2; i>=0; --i) {
if (cnt==0) ans+='A';
else {
if (a[i]<=last && dp[i][0].first<=cnt && cnt<=dp[i][0].second) ans+='A', last=a[i];
else ans+='B', --cnt, last=b[i];
}
}
reverse(ans.begin(),ans.end());
cout<<ans;
return 0;
}
if (dp[2*n-1][1].first<=n && n<=dp[2*n-1][1].second) {
string ans="B";
int cnt=n-1, last=b[2*n-1];
for (int i=2*n-2; i>=0; --i) {
if (cnt==0) ans+='A';
else {
if (a[i]<=last && dp[i][0].first<=cnt && cnt<=dp[i][0].second) ans+='A', last=a[i];
else ans+='B', --cnt, last=b[i];
}
}
reverse(ans.begin(),ans.end());
cout<<ans;
return 0;
}
cout<<-1;
}
