#include <bits/stdc++.h>
using namespace std;
#define int long long
#define f first
#define s second
const int N = 5e5 + 69;
const int inf = 1e9;
int n, a[N], b[N];
int mna1[N], mxa1[N], mna2[N], mxa2[N];
int mnb1[N], mxb1[N], mnb2[N], mxb2[N];
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
cin >> n;
n *= 2;
for (int i = 1;i <= n;i++)
cin >> a[i];
for (int i = 1;i <= n;i++)
cin >> b[i];
for (int i = 1;i <= n;i++) {
mna1[i] = mna2[i] = mnb1[i] = mnb2[i] = inf;
mxa1[i] = mxa2[i] = mxb1[i] = mxb2[i] = -inf;
}
mna1[1] = mxa1[1] = mnb2[1] = mxb2[1] = 1;
mna2[1] = mxa2[1] = mnb1[1] = mxb1[1] = 0;
for (int i = 2;i <= n;i++) {
if (a[i] >= a[i - 1]) {
mxa1[i] = max(mxa1[i], mxa1[i - 1] + 1);
mna1[i] = min(mna1[i], mna1[i - 1] + 1);
mxb1[i] = max(mxb1[i], mxb1[i - 1]);
mnb1[i] = min(mnb1[i], mnb1[i - 1]);
}
if (a[i] >= b[i - 1]) {
mxa1[i] = max(mxa1[i], mxa2[i - 1] + 1);
mna1[i] = min(mna1[i], mna2[i - 1] + 1);
mxb1[i] = max(mxb1[i], mxb2[i - 1]);
mnb1[i] = min(mnb1[i], mnb2[i - 1]);
}
if (b[i] >= a[i - 1]) {
mxa2[i] = max(mxa2[i], mxa1[i - 1]);
mna2[i] = min(mna2[i], mna1[i - 1]);
mxb2[i] = max(mxb2[i], mxb1[i - 1] + 1);
mnb2[i] = min(mnb2[i], mnb1[i - 1] + 1);
}
if (b[i] >= b[i - 1]) {
mxa2[i] = max(mxa2[i], mxa2[i - 1]);
mna2[i] = min(mna2[i], mna2[i - 1]);
mxb2[i] = max(mxb2[i], mxb2[i - 1] + 1);
mnb2[i] = min(mnb2[i], mnb2[i - 1] + 1);
}
}
if (((mna1[n] > n / 2 || mxa1[n] < n / 2) && (mnb1[n] > n / 2 || mxb1[n] < n / 2)) && ((mna2[n] > n / 2 || mxa2[n] < n / 2) && (mnb2[n] > n / 2 || mxb2[n] < n / 2)))
cout << "-1";
else {
string ans;
int x = n / 2, y = n / 2, lst = inf;
for (int i = n;i >= 1;i--) {
if (mna1[i] <= x && mxa1[i] >= x && a[i] <= lst) {
ans += 'A';
x--;
lst = a[i];
}
else if (mnb2[i] <= y && mxb2[i] >= y && b[i] <= lst) {
ans += 'B';
y--;
lst = b[i];
}
}
reverse(ans.begin(), ans.end());
cout << ans;
}
}
return 0;
}
