#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
void print() {cerr << ']' << endl;}
template<typename Head, typename... Tail> void print(Head H, Tail... T) {cerr << ' ' << H; if(sizeof...(T)) cerr << ','; print(T...); }
template<typename T> ostream& operator << (ostream& os, vector<T> v){os << "["; bool first = 1; for(auto x : v) {if(!first) os << ", "; os << x; first = 0;} os << "]"; return os;}
template<typename A, typename B> ostream& operator <<(ostream& os,pair<A, B> p) {return os << "(" << p.first << ", " << p.second << ")"; return os;}
template<typename A, typename B, typename C> ostream& operator << (ostream& os, tuple<A, B, C> a) {os << '(' << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << ")"; return os;}
template<typename A, size_t S> ostream& operator << (ostream& os, array<A, S> a) {os << "["; bool first = 1; for(auto x : a) {if(!first) os << ", "; os << x; first = 0;} os << "]"; return os;}
template<typename A> ostream& operator << (ostream& os, set<A> s) {os << "["; bool first = 1; for(auto x : s) {if(!first) os << ", "; os << x; first = 0;} os << "]"; return os;}
template<typename A, typename B> ostream& operator << (ostream& os, map<A, B> m) {os << "["; bool first = 1; for(auto x : m) {if(!first) os << ", "; os << x; first = 0;} os << "]"; return os;}
#define dbg(...) cerr << '[' << #__VA_ARGS__ << ":", print(__VA_ARGS__);
#else
#define dbg(...)
#endif // LOCAL
#define ll long long
#define vt vector
#define pb push_back
#define sz(x) int((x).size())
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
int N;
cin >> N;
vt<int> A(2 * N + 1), B(2 * N + 1);
for(int i = 1; i <= 2 * N; i++) cin >> A[i];
for(int i = 1; i <= 2 * N; i++) cin >> B[i];
vt<vt<vt<bool>>> dp(N + 1, vt<vt<bool>>(N + 1, vt<bool>(2)));
vt<vt<vt<tuple<int, int, int>>>> p(N + 1, vt<vt<tuple<int, int, int>>>(N + 1, vt<tuple<int, int, int>>(2, {-1, -1, -1})));
dp[0][0][1] = dp[0][0][0] = true;
for(int i = 0; i <= N; i++)
{
for(int j = 0; j <= N; j++)
{
if(i + j == 2 * N) continue;
for(int k = 0; k < 2; k++)
{
if(!dp[i][j][k]) continue;
int last = k ? B[j + i] : A[i + j];
if(i < N && last <= A[j + i + 1])
{
dp[i + 1][j][0] = true;
p[i + 1][j][0] = make_tuple(i, j, k);
}
if(j < N && last <= B[i + j + 1])
{
dp[i][j + 1][1] = true;
p[i][j + 1][1] = make_tuple(i, j, k);
}
}
}
}
//dbg(dp);
int idx = 0;
while(idx < 2 && !dp[N][N][idx]) idx++;
if(idx == 2)
{
cout << -1 << "\n";
return 0;
}
string ans(2 * N, '?');
for(int i = N, j = N; i > 0 || j > 0;)
{
ans[i + j - 1] = idx ? 'B' : 'A';
tie(i, j, idx) = p[i][j][idx];
}
cout << ans << "\n";
}
