#include <bits/stdc++.h>
using namespace std;
//#define int ll
using ll = long long;
using vi = vector<int>;
using ii = pair<int, int>;
using vll = vector<ll>;
const int INF = 1e9;
int main() {
cin.tie(0);
ios_base::sync_with_stdio(0);
int n;
cin >> n;
vi A(2 * n), B(2 * n);
for(int i = 0; i < 2 * n; ++i) cin >> A[i];
for(int i = 0; i < 2 * n; ++i) cin >> B[i];
///DP[poz][0 / 1] -> range cntB
vector<array<ii, 2> > DP(2 * n + 1, array<ii, 2>{ii{INF, -INF}, ii{INF, -INF}});
vector<array<ii, 2> > Orig(2 * n + 1);
DP[0][0] = {0, 0}; DP[0][1] = {1, 1};
for(int poz = 0; poz + 1 < 2 * n; ++poz) {
for(int t1 = 0; t1 < 2; ++t1) {
for(int t2 = 0; t2 < 2; ++t2) {
int v1 = (t1 ? B[poz] : A[poz]), v2 = t2 ? B[poz + 1] : A[poz + 1];
auto [mi1, ma1] = DP[poz][t1];
auto &[mi2, ma2] = DP[poz + 1][t2];
auto &[orig_mi, orig_ma] = Orig[poz + 1][t2];
if(v1 <= v2) {
if(mi1 + t2 < mi2) {
mi2 = mi1 + t2;
orig_mi = t1;
}
if(ma1 + t2 > ma2) {
ma2 = ma1 + t2;
orig_ma = t1;
}
}
}
}
}
string re;
function<void(int, int, int)> reconstruct = [&](int k, int ramas, int tip) {
///sunt la poz k, unde am pus ceva de tipul tip
int v2 = tip ? B[k] : A[k];
if(tip) re += 'B'; else re += 'A';
if(!k) return;
ramas -= tip;
for(int t1 = 0; t1 < 2; ++t1) {
int v1 = t1 ? B[k - 1] : A[k - 1];
if(v1 <= v2) {
auto [mi1, ma1] = DP[k - 1][t1];
if(mi1 <= ramas && ramas <= ma1) {
reconstruct(k - 1, ramas, t1);
break;
}
}
}
};
bool ok = false;
if(DP[2 * n - 1][0].first <= n && n <= DP[2 * n - 1][0].second) reconstruct(2 * n - 1, n, 0);
else if(DP[2 * n - 1][1].first <= n && n <= DP[2 * n - 1][1].second) reconstruct(2 * n - 1, n, 1);
reverse(re.begin(), re.end());
if(!re.empty()) cout << re << "\n";
else cout << "-1\n";
return 0;
}
