#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize ("Ofast")
typedef long long ll;
typedef long double ld;
const int MAXN = 1e6 + 25;
int n, a[MAXN][2], c[MAXN];
void solve () {
cin >> n; n *= 2;
for (int i = 1; i <= n; i++) {
cin >> a[i][0];
}
for (int i = 1; i <= n; i++) {
cin >> a[i][1];
}
int prv = 0;
for (int i = 1; i <= n; i++) {
if (a[i][0] >= prv && a[i][1] >= prv) {
if (a[i][0] <= a[i][1]) {
c[i] = 0;
prv = a[i][0];
} else {
c[i] = 1;
prv = a[i][1];
}
} else if (a[i][0] >= prv) {
c[i] = 0;
prv = a[i][0];
} else if (a[i][1] >= prv) {
c[i] = 1;
prv = a[i][1];
} else {
cout << "-1\n";
return;
}
}
/* for (int i = 1; i <= n; i++) {
cout << c[i] << " ";
}
cout << '\n';*/
int cnt[2] = {};
for (int i = 1; i <= n; i++) {
cnt[c[i]]++;
}
if (cnt[0] < cnt[1]) {
for (int i = n; i >= 1 && cnt[0] < cnt[1]; i--) {
if ((c[i] == 1) && ((i == 1 || a[i][0] >= a[i - 1][c[i - 1]]) && (i == n || a[i][0] <= a[i + 1][c[i + 1]]))) {
c[i] ^= 1; cnt[1]--; cnt[0]++;
} else if (c[i] != c[i - 1] && a[i - 1][1 - c[i - 1]] <= a[i][1 - c[i]] && a[i - 1][c[i - 1]] <= a[i - 1][1 - c[i - 1]]) {
c[i] ^= 1; c[i - 1] ^= 1;
}
}
} else if (cnt[0] > cnt[1]) {
for (int i = n; i >= 1 && cnt[0] > cnt[1]; i--) {
if ((c[i] == 0) && ((i == 1 || a[i][1] >= a[i - 1][c[i - 1]]) && (i == n || a[i][1] <= a[i + 1][c[i + 1]]))) {
c[i] ^= 1; cnt[1]++; cnt[0]--;
} else if (c[i] != c[i - 1] && a[i - 1][1 - c[i - 1]] <= a[i][1 - c[i]] && a[i - 1][c[i - 1]] <= a[i - 1][1 - c[i - 1]]) {
c[i] ^= 1; c[i - 1] ^= 1;
}
}
}
if (cnt[0] != cnt[1]) {
cout << "-1\n";
return;
}
char v[2] = {'A', 'B'};
for (int i = 1; i <= n; i++) {
cout << v[c[i]];
}
cout << '\n';
}
signed main () {
/* #ifndef ONLINE_JUDGE
freopen("input_file", "r", stdin);
freopen("output_file", "w", stdout);
#endif*/
ios::sync_with_stdio(0); cin.tie(0);
int tc = 1; //cin >> tc;
while (tc--) solve();
}
