#include <bits/stdc++.h>
using namespace std;
pair<int, int> p[4004][2][2002];
int main() {
cin.tie(0)->sync_with_stdio(0);
for (int i = 0; i < 4004; i++){
for (int k = 0; k < 2; k++){
for (int j = 0; j < 2002; j++){
p[i][k][j] = make_pair(-1, -1);
}
}
}
int n;
cin >> n;
vector<int> a(2 * n), b(2 * n);
for (int &i : a) cin >> i;
for (int &i : b) cin >> i;
vector<vector<char>> dp(2, vector<char>(n + 1));
dp[0][1] = true;
dp[1][0] = true;
for (int i = 1; i < 2 * n; i++){
vector<vector<char>> ndp(2, vector<char>(n + 1));
for (int x = 0; x <= min(n, i + 1); x++){
// c[i] = a[i]
if (x > 0){
if (dp[0][x - 1] && a[i - 1] <= a[i]){
ndp[0][x] = true;
p[i][0][x] = make_pair(0, x - 1);
}
if (dp[1][x - 1] && b[i - 1] <= a[i]){
ndp[0][x] = true;
p[i][0][x] = make_pair(1, x - 1);
}
}
// c[i] = b[i];
if (dp[0][x] && a[i - 1] <= b[i]){
ndp[1][x] = true;
p[i][1][x] = make_pair(0, x);
}
if (dp[1][x] && b[i - 1] <= b[i]){
ndp[1][x] = true;
p[i][1][x] = make_pair(1, x);
}
}
dp = ndp;
}
if (!dp[0][n] && !dp[1][n]){
cout << "-1" << endl;
return 0;
}
int i = 2 * n - 1;
int j = (dp[0][n] ? 0 : 1);
string s;
while (i >= 0){
s.push_back('A' + (j != 0));
if (i > 0 && p[i][j][n] == make_pair(-1, -1)){
assert(false);
}
pair<int, int> pp = p[i][j][n];
j = pp.first;
n = pp.second;
i--;
}
reverse(s.begin(), s.end());
cout << s << endl;
return 0;
}
