#include <bits/stdc++.h>
const int32_t MAX_N = 1e6;
const int32_t INF = 2e9;
int32_t dp[MAX_N + 5][2][2];
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
int32_t n;
std::cin >> n;
n *= 2;
std::vector< int32_t > a(n);
for(int32_t i = 0; i < n; i++) {
std::cin >> a[i];
}
std::vector< int32_t > b(n);
for(int32_t i = 0; i < n; i++) {
std::cin >> b[i];
}
dp[0][0][0] = 1;
dp[0][0][1] = 1;
dp[0][1][0] = 0;
dp[0][1][1] = 0;
for(int32_t i = 1; i < n; i++) {
dp[i][0][0] = INF;
dp[i][0][1] = -1;
dp[i][1][0] = INF;
dp[i][1][1] = -1;
if(a[i - 1] <= a[i]) {
dp[i][0][0] = std::min(dp[i][0][0], dp[i - 1][0][0] + 1);
dp[i][0][1] = std::max(dp[i][0][1], dp[i - 1][0][1] + 1);
}
if(a[i - 1] <= b[i]) {
dp[i][1][0] = std::min(dp[i][1][0], dp[i - 1][0][0]);
dp[i][1][1] = std::max(dp[i][1][1], dp[i - 1][0][1]);
}
if(b[i - 1] <= a[i]) {
dp[i][0][0] = std::min(dp[i][0][0], dp[i - 1][1][0] + 1);
dp[i][0][1] = std::max(dp[i][0][1], dp[i - 1][1][1] + 1);
}
if(b[i - 1] <= b[i]) {
dp[i][1][0] = std::min(dp[i][1][0], dp[i - 1][1][0]);
dp[i][1][1] = std::max(dp[i][1][1], dp[i - 1][1][1]);
}
}
int32_t cntA = 0, lastVal;
std::string res;
if(dp[n - 1][0][0] <= n / 2 && dp[n - 1][0][1] >= n / 2) {
cntA = 1;
lastVal = a[n - 1];
res = "A";
}
else if(dp[n - 1][1][0] <= n / 2 && dp[n - 1][1][1] >= n / 2) {
res = "B";
lastVal = b[n - 1];
}
else {
std::cout << -1 << '\n';
return 0;
}
for(int32_t i = n - 2; i >= 0; i--) {
if(a[i] <= lastVal && dp[i][0][0] <= n / 2 - cntA && dp[i][0][1] >= n / 2 - cntA) {
res += 'A';
cntA++;
lastVal = a[i];
}
else {
res += 'B';
lastVal = b[i];
}
}
std::reverse(res.begin(), res.end());
std::cout << res << '\n';
}
