#include <bits/stdc++.h>
int main() {
using namespace std;
ios_base::sync_with_stdio(0);
int n; cin >> n;
vector<int> 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];
// the dp states
vector<array<pair<int, int>, 2>> dp(2 * n);
// 0 stands for A, 1 stands for B
for (int i = 0; i < 2 * n; i++)
for (int j = 0; j < 2; j++)
dp[i][j].first = dp[i][j].second = -1;
dp[0][0] = {1, 1};
dp[0][1] = {0, 0};
for (int i = 1; i < 2 * n; i++) {
// if i end in A
if (a[i] >= a[i - 1] && dp[i - 1][0].first != -1) {
dp[i][0] = dp[i - 1][0];
dp[i][0].first++;
dp[i][0].second++;
}
if (a[i] >= b[i - 1] && dp[i - 1][1].first != -1) {
if (dp[i][0].first == -1) {
dp[i][0] = dp[i - 1][1];
dp[i][0].first++;
dp[i][0].second++;
} else {
dp[i][0].first = min(dp[i][0].first, dp[i - 1][1].first + 1);
dp[i][0].second = max(dp[i][0].second, dp[i - 1][1].second + 1);
}
}
if (b[i] >= a[i - 1] && dp[i - 1][0].first != -1) {
dp[i][1] = dp[i - 1][0];
}
if (b[i] >= b[i - 1] && dp[i - 1][1].first != -1) {
if (dp[i][1].first == -1) {
dp[i][1] = dp[i - 1][1];
} else {
dp[i][1].first = min(dp[i][1].first, dp[i - 1][1].first);
dp[i][1].second = max(dp[i][1].second, dp[i - 1][1].second);
}
}
}
auto in = [&](pair<int, int> p, int x) -> bool {
return p.first <= x && x <= p.second;
};
bool ok1 = in(dp[2 * n - 1][0], n);
bool ok2 = in(dp[2 * n - 1][1], n);
if (!ok1 && !ok2) {
cout << -1 << '\n';
} else {
int ci = 2 * n - 1, cj, cv = n;
if (ok1) {
cj = 0;
} else {
cj = 1;
}
string ans = "";
while (true) {
ans += (char) ('A' + cj);
if (ci == 0)
break;
if (cj == 0) {
if (a[ci - 1] <= a[ci] && in(dp[ci - 1][0], cv - 1)) {
cj = 0;
cv--;
} else {
cj = 1;
cv--;
}
} else {
if (a[ci - 1] <= b[ci] && in(dp[ci - 1][0], cv)) {
cj = 0;
} else {
cj = 1;
}
}
ci--;
}
reverse(ans.begin(), ans.end());
cout << ans << '\n';
}
return 0;
}
