#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
using pii = pair<int, int>;
const int MAXN = 4e3 + 5;
#define prev ___prev
int N;
int a[MAXN];
int b[MAXN];
bool dp[MAXN][MAXN][2];
array<int, 3> prev[MAXN][MAXN][2];
int ans[MAXN];
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> N;
for(int i = 1; i <= 2 * N; i++) cin >> a[i];
for(int i = 1; i <= 2 * N; i++) cin >> b[i];
dp[0][0][0] = dp[0][0][1] = true;
for(int i = 1; i <= 2 * N; i++) {
if(a[i - 1] <= a[i]) {
for(int j = 0; j <= N; j++) {
if(dp[i - 1][j][0]) {
dp[i][j][0] = true;
prev[i][j][0] = {i - 1, j, 0};
}
}
}
if(b[i - 1] <= a[i]) {
for(int j = 0; j <= N; j++) {
if(dp[i - 1][j][1]) {
dp[i][j][0] = true;
prev[i][j][0] = {i - 1, j, 1};
}
}
}
if(a[i - 1] <= b[i]) {
for(int j = 1; j <= N; j++) {
if(dp[i - 1][j - 1][0]) {
dp[i][j][1] = true;
prev[i][j][1] = {i - 1, j - 1, 0};
}
}
}
if(b[i - 1] <= b[i]) {
for(int j = 1; j <= N; j++) {
if(dp[i - 1][j - 1][1]) {
dp[i][j][1] = true;
prev[i][j][1] = {i - 1, j - 1, 1};
}
}
}
}
// for(int i = 1; i <= 2 * N; i++) {
// for(int j = 0; j <= N; j++)
// printf("%d %d %d %d\n", i, j, dp[i][j][0], dp[i][j][1]);
// }
//
// for(int i = 1; i <= 2 * N; i++) {
// for(int j = 0; j <= N; j++)
// printf("%d %d :\n %d %d %d \n %d %d %d\n", i, j, prev[i][j][0][0], prev[i][j][0][1], prev[i][j][0][2], prev[i][j][1][0], prev[i][j][1][1], prev[i][j][1][2]);
// }
if(dp[2 * N][N][0]) {
array<int, 3> cur = {2 * N, N, 0};
while(cur[0]) {
ans[cur[0]] = cur[2];
cur = prev[cur[0]][cur[1]][cur[2]];
}
for(int i = 1; i <= 2 * N; i++)
cout << (ans[i] ? 'B' : 'A');
} else if(dp[2 * N][N][1]) {
array<int, 3> cur = {2 * N, N, 1};
while(cur[0]) {
ans[cur[0]] = cur[2];
cur = prev[cur[0]][cur[1]][cur[2]];
}
for(int i = 1; i <= 2 * N; i++)
cout << (ans[i] ? 'B' : 'A');
} else cout << -1;
return (0 ^ 0);
}
