#include "bits/stdc++.h"
using namespace std;
#define INF 2000000100
#define INFLL 1000000000000000000ll
#define EPS 1e-9
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define pb push_back
#define fi first
#define sc second
using i64 = long long;
using u64 = unsigned long long;
using ld = long double;
using ii = pair<int, int>;
void solve() {
int n;
cin >> n;
n <<= 1;
vector<int> a(n), b(n);
vector<int> lisA(n), lisB(n);
vector<int> mnA(n), mxA(n);
vector<int> mnB(n), mxB(n);
for(int& v : a) cin >> v;
for(int& v : b) cin >> v;
lisA.back() = lisB.back() = 1;
mnA.back() = mxA.back() = -1;
mnB.back() = mxB.back() = 1;
auto func = [&](int& lis, int& mn, int& mx, int i, int v, int x) {
if(min(a[i + 1], b[i + 1]) >= v) {
lis = 1 + max(lisA[i + 1], lisB[i + 1]);
if(lisA[i + 1] == lisB[i + 1]) {
mn = min(mnA[i + 1], mnB[i + 1]) + x;
mx = max(mxA[i + 1], mxB[i + 1]) + x;
} else if(lisA[i + 1] > lisB[i + 1]) {
mn = mnA[i + 1] + x;
mx = mxA[i + 1] + x;
} else {
mn = mnB[i + 1] + x;
mx = mxB[i + 1] + x;
}
} else if(a[i + 1] >= v) {
lis = 1 + lisA[i + 1];
mn = mnA[i + 1] + x;
mx = mxA[i + 1] + x;
} else if(b[i + 1] >= v) {
lis = 1 + lisB[i + 1];
mn = mnB[i + 1] + x;
mx = mxB[i + 1] + x;
} else {
lis = 1;
mn = mx = x;
}
};
for(int i = n - 2; i >= 0; --i) {
func(lisA[i], mnA[i], mxA[i], i, a[i], -1);
func(lisB[i], mnB[i], mxB[i], i, b[i], 1);
}
if((lisA[0] != n || mnA[0] > 0 || mxA[0] < 0) && (lisB[0] != n || mnB[0] > 0 || mxB[0] < 0)) {
cout << "-1\n";
return;
}
string t;
int prv = 0, diff = 0;
for(int i = 0; i < n; ++i) {
if(min(a[i], b[i]) >= prv) {
if(lisA[i] >= lisB[i] && diff + mnA[i] <= 0 && diff + mxA[i] >= 0) {
--diff;
prv = a[i];
t += 'A';
} else {
++diff;
prv = b[i];
t += 'B';
}
} else if(a[i] >= prv) {
--diff;
prv = a[i];
t += 'A';
} else {
++diff;
prv = b[i];
t += 'B';
}
}
cout << t << '\n';
}
int main() {
ios_base :: sync_with_stdio(false);
cin.tie(0);
int t = 1;
// cin >> t;
while(t--) solve();
return 0;
}
