#include <bits/stdc++.h>
using namespace std;
#define ar array
#define sz(v) int(std::size(v))
using i64 = long long;
using range = ar<int, 2>;
const range unit{-1, -1};
range shift(const range one, int c) {
if (one == unit) return one;
return {one[0] + c, one[1] + c};
}
range operator+(const range one, const range two) {
if (one == unit) return two;
if (two == unit) return one;
return {min(one[0], two[0]), max(one[1], two[1])};
}
bool can(const range one, int x) {
return one[0] <= x && one[1] >= x;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
cin >> N;
int A[N * 2 + 1], B[N * 2 + 1];
A[0] = B[0] = 0;
for (int i = 1; i <= N * 2; i++) cin >> A[i];
for (int i = 1; i <= N * 2; i++) cin >> B[i];
/*
auto solve = [&]() {
ar<int, 2> dp{1, 0};
for (int i = 1; i < N * 2; i++) {
ar<int, 2> ndp{-(N * 2), -(N * 2)};
if (A[i - 1] <= A[i]) ndp[0] = max(ndp[0], dp[0] + 1);
if (B[i - 1] <= A[i]) ndp[0] = max(ndp[0], dp[1] + 1);
if (A[i - 1] <= B[i]) ndp[1] = max(ndp[1], dp[0]);
if (B[i - 1] <= B[i]) ndp[1] = max(ndp[1], dp[1]);
dp = ndp;
}
return max(dp[0], dp[1]);
};
bool ok = 1;
ok &= solve() >= N;
swap(A, B);
ok &= solve() >= N;
cout << (ok ? "YES\n" : "NO\n");
*/
range f[N * 2 + 1][2];
f[0][0] = f[0][1] = {0, 0};
for (int i = 1; i <= N * 2; i++) {
f[i][0] = f[i][1] = unit;
if (A[i - 1] <= A[i]) f[i][0] = f[i][0] + shift(f[i - 1][0], 1);
if (B[i - 1] <= A[i]) f[i][0] = f[i][0] + shift(f[i - 1][1], 1);
if (A[i - 1] <= B[i]) f[i][1] = f[i][1] + f[i - 1][0];
if (B[i - 1] <= B[i]) f[i][1] = f[i][1] + f[i - 1][1];
}
for (int t : {0, 1}) if (can(f[N * 2][t], N)) {
string S;
int i = N * 2, c = N;
while (i > 0) {
S += char('A' + t);
c -= t ^ 1;
if (A[i - 1] <= (t ? B : A)[i] && can(f[i - 1][0], c)) {
t = 0;
i--;
} else if (B[i - 1] <= (t ? B : A)[i] && can(f[i - 1][1], c)) {
t = 1;
i--;
} else assert(false);
}
reverse(begin(S), end(S));
cout << S << '\n';
return 0;
}
cout << "-1\n";
}
