#include <iostream>
#include <vector>
#include <string>
#include <climits>
using namespace std;
typedef long long ll;
const ll INF = 1e18;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
cin >> N;
int M = 2 * N;
vector<ll> A(M + 1), B(M + 1);
for (int i = 1; i <= M; ++i) cin >> A[i];
for (int i = 1; i <= M; ++i) cin >> B[i];
vector<vector<ll>> aft_min(M + 2, vector<ll>(2, INF));
vector<vector<ll>> aft_max(M + 2, vector<ll>(2, -INF));
aft_min[M][0] = aft_max[M][0] = 0;
aft_min[M][1] = aft_max[M][1] = 0;
for (int i = M - 1; i >= 1; --i) {
// 当前选A
ll minv = INF, maxv = -INF;
if (A[i] <= A[i + 1] && aft_min[i + 1][0] != INF) {
minv = min(minv, 1 + aft_min[i + 1][0]);
maxv = max(maxv, 1 + aft_max[i + 1][0]);
}
if (A[i] <= B[i + 1] && aft_min[i + 1][1] != INF) {
minv = min(minv, 0 + aft_min[i + 1][1]);
maxv = max(maxv, 0 + aft_max[i + 1][1]);
}
if (minv != INF) {
aft_min[i][0] = minv;
aft_max[i][0] = maxv;
}
// 当前选B
minv = INF, maxv = -INF;
if (B[i] <= A[i + 1] && aft_min[i + 1][0] != INF) {
minv = min(minv, 1 + aft_min[i + 1][0]);
maxv = max(maxv, 1 + aft_max[i + 1][0]);
}
if (B[i] <= B[i + 1] && aft_min[i + 1][1] != INF) {
minv = min(minv, 0 + aft_min[i + 1][1]);
maxv = max(maxv, 0 + aft_max[i + 1][1]);
}
if (minv != INF) {
aft_min[i][1] = minv;
aft_max[i][1] = maxv;
}
}
string ans;
int cntA = 0;
ll last = -INF;
for (int i = 1; i <= M; ++i) {
bool ok = false;
// 尝试选A
if (A[i] >= last && aft_min[i][0] != INF) {
ll need_min = cntA + 1 + aft_min[i][0];
ll need_max = cntA + 1 + aft_max[i][0];
if (need_min <= N && N <= need_max) {
ans.push_back('A');
cntA++;
last = A[i];
ok = true;
}
}
if (!ok) {
// 尝试选B
if (B[i] >= last && aft_min[i][1] != INF) {
ll need_min = cntA + aft_min[i][1];
ll need_max = cntA + aft_max[i][1];
if (need_min <= N && N <= need_max) {
ans.push_back('B');
last = B[i];
ok = true;
}
}
}
if (!ok) {
cout << -1 << endl;
return 0;
}
}
cout << ans << endl;
return 0;
}
