#include <bits/stdc++.h>
#define int long long
#define F first
#define S second
#define pb push_back
using namespace std;
const int N = 1e6 + 10;
const int inf = 1e15;
const int mod = 1e9 + 7;
int a[N],b[N];
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
n *= 2;
for(int i = 1; i <= n; i++) cin >> a[i];
for(int i = 1; i <= n; i++) cin >> b[i];
vector<int> mna(n + 1, 1e9), mnb(n + 1, 1e9), mxa(n + 1, -1e9), mxb(n + 1, -1e9);
mna[1] = mxa[1] = 1;
mnb[1] = mxb[1] = -1;
for(int i = 2; i <= n; i++) {
if(a[i] >= a[i - 1]) {
mxa[i] = max(mxa[i], mxa[i - 1]);
mna[i] = min(mna[i], mna[i - 1]);
}
if(a[i] >= b[i - 1]) {
mxa[i] = max(mxa[i], mxb[i - 1]);
mna[i] = min(mna[i], mnb[i - 1]);
}
if(b[i] >= a[i - 1]) {
mxb[i] = max(mxb[i], mxa[i - 1]);
mnb[i] = min(mnb[i], mna[i - 1]);
}
if(b[i] >= b[i - 1]) {
mxb[i] = max(mxb[i], mxb[i - 1]);
mnb[i] = min(mnb[i], mnb[i - 1]);
}
mxa[i]++;
mna[i]++;
mxb[i]--;
mnb[i]--;
}
if(min(mna[n], mnb[n]) > 0 || max(mxa[n], mxb[n]) < 0) {
cout << -1;
return 0;
}
int prv = inf,x = 0;
string res;
for(int i = n; i >= 1; i--) {
if(a[i] > prv) {
res += 'B';
prv = b[i];
x += 1;
continue;
}
if(b[i] > prv) {
res += 'A';
prv = a[i];
x -= 1;
continue;
}
if(x >= mna[i] && x <= mxa[i]) {
res += 'A';
prv = a[i];
x -= 1;
}else {
res += 'B';
prv = b[i];
x += 1;
}
}
reverse(res.begin(),res.end());
cout << res;
return 0;
}
