#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
n *= 2;
vector<int> a(n), b(n);
for(int i = 0; i < n; i++) cin >> a[i];
for(int i = 0; i < n; i++) cin >> b[i];
vector<int> mna(n, 1e9), mnb(n, 1e9), mxa(n, -1e9), mxb(n, -1e9);
mna[0] = mxa[0] = 1;
mnb[0] = mxb[0] = -1;
for(int i = 1; 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 - 1], mnb[n - 1]) > 0 || max(mxa[n - 1], mxb[n - 1]) < 0) {
cout << -1;
return 0;
}
string s;
bool oka = true, okb = true;
int border = 0;
for(int i = n - 1; i >= 0; i--) {
if(oka) {
if(mna[i] <= border && border <= mxa[i]) {
s += 'A';
border--;
oka = (a[i] >= a[i - 1]);
okb = (a[i] >= b[i - 1]);
continue;
}
}
if(okb) {
if(mnb[i] <= border && border <= mxb[i]) {
s += 'B';
border++;
oka = (b[i] >= a[i - 1]);
okb = (b[i] >= b[i - 1]);
}
}
}
reverse(s.begin(), s.end());
cout << s;
return 0;
}
