// 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 a[N], b[N];
int dp[N], ri[N];
bool mark[N], vis[N];
int main() {
ios :: sync_with_stdio(0), cin.tie(0); cout.tie(0);
int n; cin >>n;
for(int i = 0; i < 2 * n; i++) cin >>a[i];
for(int i = 0; i < 2 * n; i++) cin >>b[i];
vector<int> vc;
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]}});
}
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 = 0;
for(int j = l; j <= r; j++) {
if(!vis[j]) {
if(vc[j] == a[j]) val -= 2;
else val += 2;
}
}
if(val < 0) {
return cout<<-1, 0;
}
if(val + cnt > 0) continue;
cnt += val;
for(int j = l; j <= r; j++) {
if(vis[j]) continue;
vis[j] = 1;
if(s[j] == 'A') s[j] = 'B';
else s[j] = '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();
for(int j = l; j <= r; j++) {
if(!vis[j]) {
if(vc[j] == a[j]) val -= 2;
else val += 2;
}
}
if(val > 0) {
return cout<<-1, 0;
}
if(val + cnt < 0) continue;
cnt += val;
for(int j = l; j <= r; j++) {
if(vis[j]) continue;
vis[j] = 1;
if(s[j] == 'A') s[j] = 'B';
else s[j] = 'A';
}
}
if(cnt > 0) return cout<<-1, 0;
return cout<<s, 0;
}
