#include <iostream>
#include <vector>
#include <limits>
#include <string>
#include <cassert>
#include <algorithm>
using namespace std;
int main(){
cin.tie(0);
ios_base::sync_with_stdio(false);
int n; cin >> n; n <<= 1;
vector<pair<int, int>> ops (n);
for (int i = 0; i < n; ++i) cin >> ops[i].first;
for (int i = 0; i < n; ++i) cin >> ops[i].second;
vector<pair<int, int>> lowers (n, {numeric_limits<int>::max(), numeric_limits<int>::max()}), uppers (n, {numeric_limits<int>::min(), numeric_limits<int>::min()});
lowers[0].first = 1; lowers[0].second = 0;
uppers[0].first = 1; uppers[0].second = 0;
for (int i = 1; i < n; ++i) {
if (ops[i].first >= ops[i - 1].first) {
lowers[i].first = lowers[i - 1].first;
uppers[i].first = uppers[i - 1].first;
}
if (ops[i].first >= ops[i - 1].second) {
lowers[i].first = min(lowers[i].first, lowers[i - 1].second);
uppers[i].first = max(uppers[i].first, uppers[i - 1].second);
}
if (lowers[i].first != numeric_limits<int>::max()) lowers[i].first++;
uppers[i].first++;
if (ops[i].second >= ops[i - 1].first) {
lowers[i].second = lowers[i - 1].first;
uppers[i].second = uppers[i - 1].first;
}
if (ops[i].second >= ops[i - 1].second) {
lowers[i].second = min(lowers[i].second, lowers[i - 1].second);
uppers[i].second = max(uppers[i].second, uppers[i - 1].second);
}
}
auto isin = [](int l, int r, int v){
return l <= v && v <= r;
};
if (!isin(lowers.back().first, uppers.back().first, n/2) && !isin(lowers.back().second, uppers.back().second, n/2)) cout << -1 << "\n";
else {
string ANS;
int tbd = n/2;
int at = numeric_limits<int>::max();
for (int i = n - 1; i >= 0; --i) {
if (isin(lowers[i].first, uppers[i].first, tbd) && at >= ops[i].first){
ANS.push_back('A');
tbd--;
at = ops[i].first;
}
else if (isin(lowers[i].second, uppers[i].second, tbd) && at >= ops[i].second){
ANS.push_back('B');
at = ops[i].second;
}
else{
assert(false);
}
}
assert(tbd == 0);
reverse(ANS.begin(), ANS.end());
cout << ANS;
}
return 0;
}
