#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define pb push_back
#define ff first
#define ss second
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n; cin>>n;
int m = 2 * n;
vector<int> a(m + 1), b(m + 1);
for (int i = 1; i <= m; i++) cin>>a[i];
for (int i = 1; i <= m; i++) cin>>b[i];
pii rr[m + 1][2];
rr[1][0] = {1, 1};
rr[1][1] = {0, 0};
const int inf = 1e9;
int l1, r1;
for (int i = 2; i <= m; i++){
l1 = inf; r1 = 0;
if (a[i - 1] <= a[i] && rr[i - 1][0].ff != -1){
l1 = min(l1, rr[i - 1][0].ff + 1);
r1 = max(r1, rr[i - 1][0].ss + 1);
}
if (b[i - 1] <= a[i] && rr[i - 1][1].ff != -1){
l1 = min(l1, rr[i - 1][1].ff + 1);
r1 = max(r1, rr[i - 1][1].ss + 1);
}
if (l1 <= r1) rr[i][0] = {l1, r1};
else rr[i][0] = {-1, -1};
l1 = inf; r1 = 0;
if (a[i - 1] <= b[i] && rr[i - 1][0].ff != -1){
l1 = min(l1, rr[i - 1][0].ff);
r1 = max(r1, rr[i - 1][0].ss);
}
if (b[i - 1] <= b[i] && rr[i - 1][1].ff != -1){
l1 = min(l1, rr[i - 1][1].ff);
r1 = max(r1, rr[i - 1][1].ss);
}
if (l1 <= r1) rr[i][1] = {l1, r1};
else rr[i][1] = {-1, -1};
}
auto get = [&](int x, int y, int b){
return (rr[x][b].ff <= y && y <= rr[x][b].ss);
};
if (get(m, n, 0) || get(m, n, 1)){
vector<bool> all;
int i = m, j = n, c = get(m, n, 0) ? 0 : 1;
while (true){
all.pb(c);
if (i == 1) break;
if (c){
if (a[i - 1] <= b[i] && get(i - 1, j, 0)){
c = 0;
}
}
else {
if (b[i - 1] <= a[i] && get(i - 1, j - 1, 1)){
c = 1;
}
j--;
}
i--;
}
reverse(all.begin(), all.end());
for (bool i: all) cout<<((i) ? "B" : "A");
cout<<"\n";
}
else {
cout<<-1<<"\n";
}
}
