#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
const int inf = 1e9 + 9;
bool inside(pair<int, int> a, int p){
return (p >= a.f && p <= a.sc);
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n; cin >> n;
vector<int> a(2*n), b(2*n);
for(int &x: a) cin >> x;
for(int &x: b) cin >> x;
vector<pair<int, int>> dpa(2*n), dpb(2*n);
dpa[0] = {1, 1};
dpb[0] = {0, 0};
for(int i = 1; i < 2*n; i++){
auto [al, ar] = dpa[i-1];
auto [bl, br] = dpb[i-1];
{
int l1 = -1, r1 = -1, l2 = -1, r2 = -1;
if(a[i] >= a[i-1] && al != -1) l1 = al+1, r1 = ar+1;
if(a[i] >= b[i-1] && bl != -1) l2 = bl+1, r2 = br+1;
if(l1 == -1 && l2 == -1){
dpa[i] = {-1, -1};
}
else if(l1 == -1){
dpa[i] = {l2, r2};
}
else if(l2 == -1){
dpa[i] = {l1, r1};
}
else{
if(l1 > l2) swap(l1, l2), swap(r1, r2);
dpa[i] = {min(l1, l2), max(r1, r2)};
}
}
{
int l1 = -1, r1 = -1, l2 = -1, r2 = -1;
if(b[i] >= a[i-1] && al != -1) l1 = al, r1 = ar;
if(b[i] >= b[i-1] && bl != -1) l2 = bl, r2 = br;
if(l1 == -1 && l2 == -1){
dpb[i] = {-1, -1};
}
else if(l1 == -1){
dpb[i] = {l2, r2};
}
else if(l2 == -1){
dpb[i] = {l1, r1};
}
else{
if(l1 > l2) swap(l1, l2), swap(r1, r2);
dpb[i] = {min(l1, l2), max(r1, r2)};
}
}
}
if(!inside(dpa[2*n-1], n) && !inside(dpb[2*n-1], n)){
cout << "-1\n";
exit(0);
}
str ans = "";
str cur;
if(inside(dpa[2*n-1], n)) cur = "A";
else cur = "B";
int cnt = n;
for(int i = 2*n-1; i >= 0; i--){
ans+=cur;
if(cur == "A") cnt--;
if(i > 0){
if(inside(dpa[i-1], cnt) && (cur == "A" ? a:b)[i] >= a[i-1]) cur = "A";
else cur = "B";
}
}
reverse(ans.begin(), ans.end());
cout << ans << "\n";
}
