#include <bits/stdc++.h>
using namespace std;
const int N = 1000005;
int a[N], b[N]; bool inq[N];
queue<int> que;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n; cin >> n; int m = n; n <<= 1;
for (int i = 0; i < n; i++)
cin >> a[i];
for (int i = 0; i < n; i++)
cin >> b[i];
for (int i = 0; i + 1 < n; i++) {
inq[i] = 1; que.push(i);
}
while (que.size()) {
int i = que.front(), mn, mx;
inq[i] = 0; que.pop();
if (a[i] < 0 && b[i] < 0)
return cout << -1, 0;
if (a[i + 1] < 0 && b[i + 1] < 0)
return cout << -1, 0;
if (a[i] < 0) mn = b[i];
else if (b[i] < 0) mn = a[i];
else mn = min(a[i], b[i]);
mx = max(a[i + 1], b[i + 1]);
bool flag = 0;
if (a[i] > mx) {
a[i] = -1; flag = 1;
}
if (b[i] > mx) {
b[i] = -1; flag = 1;
}
if (a[i + 1] > 0 && a[i + 1] < mn) {
a[i + 1] = -1; flag = 1;
}
if (b[i + 1] > 0 && b[i + 1] < mn) {
b[i + 1] = -1; flag = 1;
}
if (flag) {
que.push(i); inq[i] = 1;
if (i > 0 && !inq[i - 1]) {
que.push(i - 1); inq[i - 1] = 1;
}
if (i + 2 < n && !inq[i + 1]) {
que.push(i + 1); inq[i + 1] = 1;
}
}
}
int curl = 0, curr = 0;
vector<tuple<int, int, int, int>> vec;
for (int i = 0; i < n; i++) {
if (a[i] < 0 || b[i] < 0) {
if (a[i] > 0) {
curl++; curr++;
vec.emplace_back(i, i, 1, 1);
} else vec.emplace_back(i, i, 0, 0);
continue;
}
int j = i;
while (j + 1 < n && a[j + 1] > 0
&& b[j + 1] > 0 && min(a[j + 1],
b[j + 1]) < max(a[j], b[j])) j++;
int cnt = 0;
for (int k = i; k <= j; k++)
if (a[k] > b[k]) cnt++;
int tmpl = cnt, tmpr = cnt;
for (int k = i; k <= j; k++) {
if (a[k] > b[k]) cnt--;
else cnt++;
tmpl = min(tmpl, cnt);
tmpr = max(tmpr, cnt);
}
vec.emplace_back(i, j, tmpl, tmpr);
curl += tmpl; curr += tmpr; i = j;
}
if (curl > m || curr < m)
return cout << -1, 0;
for (auto pp : vec)
m -= get<2> (pp);
for (auto pp : vec) {
int i, j, l, r;
tie(i, j, l, r) = pp;
if (a[i] < 0 || b[i] < 0) {
cout << (a[i] > 0 ? 'A' : 'B');
continue;
}
int need = l + min(m, r - l);
m -= min(m, r - l);
for (int k = i; k <= j; k++)
if (a[k] > b[k]) need--;
if (!need) {
for (int k = i; k <= j; k++)
cout << (a[k] > b[k] ? 'A' : 'B');
goto gg;
}
for (int k = i; k <= j; k++) {
if (a[k] > b[k]) need++;
else need--;
if (need == 0) {
for (int q = i; q <= k; q++)
cout << (a[k] > b[k] ? 'B' : 'A');
for (int q = k + 1; q <= j; q++)
cout << (a[k] > b[k] ? 'A' : 'B');
goto gg;
}
}
gg:;
}
assert(m == 0);
}
