#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int maxn = 500005;
int n, a[2*maxn], b[2*maxn];
pair<int,int> dp[2*maxn][2];
pair<int,int> merge(pair<int,int> a, pair<int,int> b) {
if (a.first == -1) return b;
if (b.first == -1) return a;
return {min(a.first,b.first),max(a.second,b.second)};
}
string res;
void recon(int i, int j, int k) {
if (i == 0) {
reverse(res.begin(),res.end());
cout << res << '\n';
exit(0);
}
res += j ? 'B' : 'A';
if (j == 0) {
--k;
if (a[i] >= a[i-1] && dp[i-1][0].first <= k && k <= dp[i-1][0].second) {
recon(i-1,0,k);
}
else {
recon(i-1,1,k);
}
}
else {
if (b[i] >= a[i-1] && dp[i-1][0].first <= k && k <= dp[i-1][0].second) {
recon(i-1,0,k);
}
else {
recon(i-1,1,k);
}
}
}
int main() {
cin >> n;
for (int i = 1; i <= 2*n; i++) {
cin >> a[i];
}
for (int i = 1; i <= 2*n; i++) {
cin >> b[i];
}
for (int i = 0; i < 2*maxn; i++) {
for (int j = 0; j < 2; j++) {
dp[i][j] = {-1,-1};
}
}
dp[0][0] = dp[1][0] = {0,0};
for (int i = 1; i <= 2*n; i++) {
if (a[i] >= a[i-1]) dp[i][0] = merge(dp[i][0],dp[i-1][0]);
if (a[i] >= b[i-1]) dp[i][0] = merge(dp[i][0],dp[i-1][1]);
if (dp[i][0].first != -1) {
++dp[i][0].first; ++dp[i][0].second;
}
if (b[i] >= a[i-1]) dp[i][1] = merge(dp[i][1],dp[i-1][0]);
if (b[i] >= b[i-1]) dp[i][1] = merge(dp[i][1],dp[i-1][1]);
//printf("[%d][0]: (%d, %d)\n",i,dp[i][0].first,dp[i][0].second);
//printf("[%d][1]: (%d, %d)\n",i,dp[i][1].first,dp[i][1].second);
}
if (dp[2*n][0].first <= n && n <= dp[2*n][0].second) {
recon(2*n,0,n);
}
else if (dp[2*n][1].first <= n && n <= dp[2*n][1].second) {
recon(2*n,1,n);
}
else {
cout << -1 << '\n';
}
}
