#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vl vector<ll>
#define vii vector<pii>
#define vll vector<pll>
using namespace std;
const int maxn = 5e5;
int n;
pair<int, char>p[2][2 * maxn];
bool b[2][2 * maxn];
char ans[2 * maxn];
vector<array<int, 4> >r;
int main()
{
cin>>n;
for(int j : {0 , 1}){
for(int i = 0; i < 2 * n; i++){
cin>>p[j][i].first;
p[j][i].second = 'A' + j;
}
}
for(int i = 0; i < 2 * n; ++i){
if(p[0][i].first > p[1][i].first)
swap(p[0][i], p[1][i]);
if(i > 0){
if(p[0][i - 1].first > p[1][i].first){
cout<<-1<<endl;
return 0;
}
if(p[1][i - 1].first > p[1][i].first)
{
b[0][i - 1] = 1;
}
if(p[0][i].first < p[0][i - 1].first){
b[1][i] = 1;
}
if(p[0][i].first < p[1][i - 1].first){
if(b[1][i - 1])
b[1][i] = 1;
}
}
}
//assert(false);
for(int i = 2 * n - 1; i ; --i){
if(p[0][i].first < p[1][i - 1].first){
if(b[0][i])
b[0][i - 1] = 1;
}
}
//assert(false);
for(int i = 0; i <2 * n; i++){
if(b[0][i] && b[1][i]){
cout<<-1<<endl;
return 0;
}
}
//assert(false);
int l[2]={n, n};
for(int i = 0; i < 2 * n; ++i){
for(int j : {0, 1}){
if(b[j][i]){
ans[i] = p[j][i].second;
--l[p[j][i].second - 'A'];
}
}
}
//assert(false);
int rez1 = 0, rez2 = 0;
for(int i = 0, j = 0; i < 2 * n; i=j){
if(b[0][i] || b[1][i]){
++j;
continue;
}
for(++j; j < 2 * n && !b[0][j] && !b[1][j] && p[0][j].first < p[1][j - 1].first; ++j);
int c = 0;
for(int k = i; k < j; ++k){
c+=p[0][k].second == 'A';
}
int mn = c, mx = c;
for(int k = j - 1; k >= i; --k){
c-=p[0][k].second == 'A';
c+=p[1][k].second == 'A';
mn = min(mn,c);
mx = max(mx, c);
}
r.push_back({i,j, mn, mx});
rez1 += mn;
rez2 += mx;
}
if(l[0] < rez1 || l[0] > rez2)
{
cout<<-1<<endl;
return 0;
}
l[0] -= rez1;
for(array<int, 4> ri : r){
int need = min(l[0],ri[3] - ri[2]);
l[0]-=need;
int c = 0;
for(int k = ri[0]; k < ri[1]; ++k){
c+=p[0][k].second =='A';
ans[k] = p[0][k].second;
}
if(c - ri[2] == need){
continue;
}
for(int k = ri[1] - 1; k >= ri[0]; --k){
c-=p[0][k].second == 'A';
c+=p[1][k].second == 'A';
ans[k] = p[1][k].second;
if(c - ri[2] == need){
break;
}
}
}
for(int i = 0; i < 2 * n; i++){
cout<<ans[i];
}
}
