#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];
const int N = 2e3 + 1;
bitset<N> bt[m + 1][2];
bt[1][0].set(1, 1);
bt[1][1].set(0, 1);
for (int i = 2; i <= m; i++){
if (a[i - 1] <= a[i]) bt[i][0] |= (bt[i - 1][0] << 1);
if (b[i - 1] <= a[i]) bt[i][0] |= (bt[i - 1][1] << 1);
if (a[i - 1] <= b[i]) bt[i][1] |= bt[i - 1][0];
if (b[i - 1] <= b[i]) bt[i][1] |= bt[i - 1][1];
}
auto get = [&](int x, int y, int b){
return bt[x][b][y];
};
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";
}
}
