#include <bits/stdc++.h>
using namespace std;
const int N = 1'000'000;
int n, a[2][N + 10];
pair<int, int> seg[2][N + 10];
char ans[N + 10];
void readInput() {
cin >> n;
for (int i = 1; i <= n + n; i++)
cin >> a[1][i];
for (int i = 1; i <= n + n; i++)
cin >> a[0][i];
}
pair<int, int> merg(pair<int, int> a, pair<int, int> b) {
if (a.first == -1)
return b;
if (b.first == -1)
return a;
return {min(a.first, b.first), max(a.second, b.second)};
}
pair<int, int> calc(int val, int mn, int mx, int id) {
if (val < a[mn][id])
return {-1, -1};
if (val < a[mx][id])
return seg[mn][id];
return merg(seg[mn][id], seg[mx][id]);
}
pair<int, int> add(pair<int, int> a) {
if (a.first == -1)
return a;
return {a.first + 1, a.second + 1};
}
void calcDP() {
seg[1][1] = {1, 1};
seg[0][1] = {0, 0};
for (int i = 2; i <= n + n; i++) {
int mn = (a[0][i - 1] <= a[1][i - 1]? 0: 1);
int mx = 1 - mn;
seg[1][i] = add(calc(a[1][i], mn, mx, i - 1));
seg[0][i] = calc(a[0][i], mn, mx, i - 1);
}
}
bool isIn(pair<int, int> seg, int x) {
return seg.first <= x && x <= seg.second;
}
void calcAns() {
int idx = n + n, need = n;
int t = (isIn(seg[0][n + n], n)? 0: 1);
while (true) {
ans[idx] = (t == 0? 'B': 'A');
need -= t;
if (idx == 1)
break;
if (isIn(seg[0][idx - 1], need) && a[0][idx - 1] <= a[t][idx])
t = 0;
else
t = 1;
idx--;
}
}
void writeOutput() {
if (isIn(seg[0][n + n], n) || isIn(seg[1][n + n], n)) {
calcAns();
for (int i = 1; i <= n + n; i++)
cout << ans[i];
}
else
cout << -1;
cout.flush();
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
readInput();
calcDP();
writeOutput();
return 0;
}
