#include<bits/stdc++.h>
typedef long long ll;
#define fi first
#define se second
#define pii pair<ll,ll>
#define inf 1e9
#define N 1000006
using namespace std;
ll n, m;
ll a[N], b[N], dd[N];
ll f[4002][2002][2];
ll dp(ll i, ll j, ll tt) {
if (i > n * 2) {
if (j == n) {
return 1;
}
return 0;
}
if (f[i][j][tt] != -1) {
return f[i][j][tt];
}
ll last = a[i - 1];
if (tt == 1) {
last = b[i - 1];
}
ll res = 0;
if (a[i] >= last && j <= n) {
res = max(res, dp(i + 1, j + 1, 0));
}
if (b[i] >= last) {
res = max(res, dp(i + 1, j, 1) );
}
f[i][j][tt] = res;
return res;
}
pii f2[N][2];
pii merge(pii a, pii b, ll u) {
return {min(a.fi, b.fi + u), max(a.se, b.se + u)};
}
pii dp2(ll i, ll tt) {
if (i > n + n) {
return {0, 0};
}
if (f2[i][tt].fi != -1) {
return f2[i][tt];
}
pii res = {inf, -inf};
ll last = a[i - 1];
if (tt == 1) {
last = b[i - 1];
}
if (a[i] >= last) {
res = merge(res, dp2(i + 1, 0), 1);
}
if (b[i] >= last) {
res = merge(res, dp2(i + 1, 1), 0);
}
f2[i][tt] = res;
return res;
}
void trace(ll i, ll j, ll tt) {
if (i > n * 2) {
return;
}
ll last = a[i - 1];
if (tt == 1) {
last = b[i - 1];
}
if (a[i] >= last && j <= n) {
//res = max(res, dp(i + 1, j + 1, 0));
if (dp(i + 1, j + 1, 0) == 1) {
dd[i] = 1;
trace(i + 1, j + 1, 0);
return;
}
}
if (b[i] >= last) {
//res = max(res, dp(i + 1, j, 1) );
if (dp(i + 1, j, 1) == 1) {
trace(i + 1, j, 1);
return;
}
}
}
void sub1() {
memset(f, -1, sizeof(f));
ll x = dp(1, 0, 0);
if (x == 0) {
cout << -1;
return;
}
trace(1, 0, 0);
for (int i = 1; i <= n + n; i ++) {
if (dd[i]) {
cout << "A";
}
else {
cout << "B";
}
}
}
void trace2(ll i, ll tt, ll used) {
if (i > n + n) return;
ll last = a[i - 1];
if (tt == 1) {
last = b[i - 1];
}
if (a[i] >= last) {
pii res = dp2(i + 1, 0);
if (res.fi + 1 <= used && used <= res.se + 1) {
dd[i] = 1;
trace2(i + 1, 0, used - 1);
return;
}
}
if (b[i] >= last) {
pii res = dp2(i + 1, 1);
if (res.fi <= used && used <= res.se) {
dd[i] = 0;
trace2(i + 1, 1, used);
return;
}
}
}
void sub2() {
for (int i = 0; i <= n + n; i ++) {
f2[i][0].fi = -1;
f2[i][1].fi = -1;
}
pii res = dp2(1, 0);
ll used = n;
if (!(res.fi <= used && used <= res.se)) {
cout << -1;
}
else {
trace2(1, 0, used);
for (int i = 1; i <= n + n; i ++) {
if (dd[i] == 1) {
cout << "A";
}
else {
cout << "B";
}
}
}
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
for (int i = 1; i <= n + n; i ++) {
cin >> a[i];
}
for (int i = 1; i <= n + n; i ++) {
cin >> b[i];
}
sub2();
return 0;
}
