// oooo
/*
har chi delet mikhad bebar ~
gitar o ba khodet nabar! ~
;Amoo_Hasan;
*/
#include<bits/stdc++.h>
//#pragma GCC optimize("O3,no-stack-protector,unroll-loops")
//#pragma GCC target("avx2,fma")
using namespace std;
typedef long long ll;
typedef long double ld;
#define Sz(x) int((x).size())
#define All(x) (x).begin(), (x).end()
#define wtf(x) cout<<#x <<" : " <<x <<endl
#define mak make_pair
//constexpr int PRI = 1000696969;
constexpr ll INF = 1e18, N = 1e6 + 10, MOD = 1e9 + 7;
int n;
int a[N], b[N];
int dp[N], ri[N];
bool mark[N], vis[N];
vector<int> vc;
struct node {
int lz, cnt;
node() {
cnt = lz = 0;
}
} x[N << 2];
void build(int l = 0, int r = 2 * n, int v = 1) {
if(r - l < 2) {
if(!mark[l]) {
if(vc[l] == a[l]) x[v].cnt = -2;
else x[v].cnt = 2;
}
return;
}
int mid = (l + r) >> 1;
build(l, mid, 2 * v), build(mid, r, 2 * v + 1);
x[v].cnt = x[2 * v].cnt + x[2 * v + 1].cnt;
}
void put(int l, int r, int v) {
if(x[v].lz == 0) return;
x[2 * v].cnt = 0, x[2 * v].lz = 1;
x[2 * v + 1].cnt = 0, x[2 * v + 1].lz = 1;
x[v].lz = 0;
}
void change(int s, int e, int l = 0, int r = 2 * n, int v = 1) {
if(r <= s || l >= e) return;
if(l >= s && r <= e) {
x[v].cnt = 0, x[v].lz = 1;
return;
}
put(l, r, v);
int mid = (l + r) >> 1;
change(s, e, l, mid, 2 * v), change(s, e, mid, r, 2 * v + 1);
x[v].cnt = x[2 * v].cnt + x[2 * v + 1].cnt;
}
int get(int s, int e, int l = 0, int r = 2 * n, int v = 1) {
if(r <= s || l >= e) return 0;
if(l >= s && r <= e) return x[v].cnt;
put(l, r, v);
int mid = (l + r) >> 1;
return get(s, e, l, mid, 2 * v) + get(s, e, mid, r, 2 * v + 1);
}
int main() {
ios :: sync_with_stdio(0), cin.tie(0); cout.tie(0);
cin >>n;
for(int i = 0; i < 2 * n; i++) cin >>a[i];
for(int i = 0; i < 2 * n; i++) cin >>b[i];
for(int i = 0; i < 2 * n; i++) {
if(!vc.empty() && max(a[i], b[i]) < vc.back()) return cout<<-1, 0;
int val = min(a[i], b[i]);
if(vc.empty() || vc.back() <= val) vc.push_back(val);
else vc.push_back(max(a[i], b[i]));
}
string s = "";
for(int j = 0; j < Sz(vc); j++) {
if(vc[j] == a[j]) s.push_back('A');
else s.push_back('B');
}
int cnt = 0;
for(int j = 0; j < Sz(vc); j++) {
if(vc[j] == a[j]) cnt++;
else cnt--;
}
if(cnt == 0) {
return cout<<s, 0;
}
vector<pair<int, pair<int, int> > > nap;
for(int i = 2 * n - 1; i >= 0; i--) {
if(vc[i] != min(a[i], b[i])) continue;
if(i == 2 * n - 1) {
if(vc[i] == a[i]) dp[i] = -2;
else dp[i] = 2;
ri[i] = i;
nap.push_back({dp[i], {i, i}});
continue;
}
if(max(a[i], b[i]) > max(a[i + 1], b[i + 1])) {
mark[i] = 1;
continue;
}
if(max(a[i], b[i]) <= vc[i + 1]) {
if(vc[i] == a[i]) dp[i] = -2;
else dp[i] = 2;
ri[i] = i;
nap.push_back({dp[i], {i, i}});
continue;
}
if(mark[i + 1]) {
mark[i] = 1;
continue;
}
dp[i] = dp[i + 1];
if(vc[i] == a[i]) dp[i] -= 2;
else dp[i] += 2;
ri[i] = ri[i + 1];
nap.push_back({dp[i], {i, ri[i]}});
}
build();
sort(All(nap));
if(cnt < 0) {
while(!nap.empty() && cnt < 0) {
int val = nap.back().first, l = nap.back().second.first, r = nap.back().second.second;
nap.pop_back();
val = get(l, r + 1);
if(val < 0) {
//return cout<<-1, 0;
continue;
}
if(val + cnt > 0) continue;
cnt += val;
change(l, r + 1);
}
for(int i = 0; i < 2 * n; i++) {
if(mark[i]) continue;
if(get(i, i + 1) == 0) {
if(s[i] == 'A') s[i] = 'B';
else s[i] = 'A';
}
}
if(cnt < 0) return cout<<-1, 0;
return cout<<s, 0;
}
reverse(All(nap));
while(!nap.empty() && cnt > 0) {
int val = nap.back().first, l = nap.back().second.first, r = nap.back().second.second;
nap.pop_back();
val = get(l, r + 1);
if(val > 0) {
//return cout<<-1, 0;
continue;
}
if(val + cnt < 0) continue;
cnt += val;
change(l, r + 1);
}
for(int i = 0; i < 2 * n; i++) {
if(mark[i]) continue;
if(get(i, i + 1) == 0) {
if(s[i] == 'A') s[i] = 'B';
else s[i] = 'A';
}
}
if(cnt > 0) return cout<<-1, 0;
return cout<<s, 0;
}
