#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];
bool dp[m + 1][n + 1][2];
for (int i = 1; i <= m; i++){
for (int j = 1; j <= n; j++){
dp[i][j][0] = dp[i][j][1] = 0;
}
}
dp[1][1][0] = dp[1][0][1] = 1;
for (int i = 2; i <= m; i++){
for (int j = 0; j <= n; j++){
if (j > 0 && a[i - 1] <= a[i]) dp[i][j][0] = max(dp[i][j][0], dp[i - 1][j - 1][0]);
if (j > 0 && b[i - 1] <= a[i]) dp[i][j][0] = max(dp[i][j][0], dp[i - 1][j - 1][1]);
if (a[i - 1] <= b[i]) dp[i][j][1] = max(dp[i][j][1], dp[i - 1][j][0]);
if (b[i - 1] <= b[i]) dp[i][j][1] = max(dp[i][j][1], dp[i - 1][j][1]);
}
}
if (dp[m][n][0] || dp[m][n][1]){
vector<bool> all;
int i = m, j = n, c = (dp[m][n][0]) ? 0 : 1;
while (true){
all.pb(c);
if (i == 1) break;
if (c){
if (a[i - 1] <= b[i] && dp[i - 1][j][0]){
c = 0;
}
}
else {
if (b[i - 1] <= a[i] && dp[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";
}
}
