#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pii pair<int, int>
#define pll pair<ll, ll>
int n;
const int maxn = 1000010;
int a[maxn];
int b[maxn];
pii rg[maxn][2];
int res[maxn]; //0 for A, 1 for B
pii urange(pii u, pii v) {
if (u.first == -1) return v;
if (v.first == -1) return u;
return {min(u.first, v.first), max(u.second, v.second)};
}
bool isin(int val, pii br) {
return val >= br.first && val <= br.second;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
for (int i = 1; i <= 2*n; i++) {
cin >> a[i];
}
for (int i = 1; i <= 2*n; i++) {
cin >> b[i];
}
// set A initial values to be 1 of each
rg[1][0] = {1, 1};
rg[1][1] = {0, 0};
for (int i = 2; i <= 2*n; i++) {
rg[i][0] = {-1, -1};
rg[i][1] = {-1, -1};
if (a[i-1] <= a[i]) {
rg[i][0] = urange(rg[i][0], rg[i-1][0]);
}
if (b[i-1] <= a[i]) {
rg[i][0] = urange(rg[i][0], rg[i-1][1]);
}
if (a[i-1] <= b[i]) {
rg[i][1] = urange(rg[i][1], rg[i-1][0]);
}
if (b[i-1] <= b[i]) {
rg[i][1] = urange(rg[i][1], rg[i-1][1]);
}
if (rg[i][0].first != -1) {
rg[i][0] = {rg[i][0].first+1, rg[i][0].second+1};
}
// cout << i << " : " << rg[i][0].first << " " << rg[i][0].second
// << " -- " << rg[i][1].first << " " << rg[i][1].second << endl;
}
int indo = -1;
if (isin(n, rg[2*n][0])) indo = 0;
if (isin(n, rg[2*n][1])) indo = 1;
res[2*n] = indo;
if (indo == -1) {
cout << -1 << endl;
return 0;
}
int ctarg = n;
for (int i = 2*n-1; i >= 1; i--) {
if (indo == 0) ctarg--;
int nindo = -1;
int cval = a[i+1];
if (indo == 1) cval = b[i+1];
if (isin(ctarg, rg[i][0]) && a[i] <= cval) {
nindo = 0;
}
else nindo = 1;
indo = nindo;
res[i] = indo;
}
for (int i = 1; i <= 2*n; i++) {
if (res[i] == 0) cout << "A";
else cout << "B";
}
cout << endl;
}
