#include <bits/stdc++.h>
#define ar array
//#define int long long
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const ll inf = 1e18;
const int maxn = 1e5 + 5;
signed main() {
int n; cin >> n;
int a[2][2*n+1];
for(int i=0; i<2; i++)
for(int j=1; j<=2*n; j++) cin >> a[i][j];
ar<int, 3> par[2*n+1][n+1][2];
int dp[2*n+1][n+1][2];
memset(dp, 0, sizeof(dp));
for(int i=0; i<=2*n; i++)
for(int j=0; j<=n; j++)
for(int k=0; k<2; k++) par[i][j][k] = { -1, -1, -1 };
dp[1][1][0] = 1;
dp[1][0][1] = 1;
for(int i=2; i<=2*n; i++) {
for(int j=0; j<=n; j++) {
if(j > 1 && dp[i-1][j-1][0] && a[0][i-1] <= a[0][i]) {
dp[i][j][0] = 1;
par[i][j][0] = { i-1, j-1, 0 };
}
if(j && dp[i-1][j-1][1] && a[1][i-1] <= a[0][i]) {
dp[i][j][0] = 1;
par[i][j][0] = { i-1, j-1, 1 };
}
if(j && dp[i-1][j][0] && a[0][i-1] <= a[1][i]) {
dp[i][j][1] = 1;
par[i][j][1] = { i-1, j, 0 };
}
if(dp[i-1][j][1] && a[1][i-1] <= a[1][i]) {
dp[i][j][1] = 1;
par[i][j][1] = { i-1, j, 1 };
}
}
}
if(!dp[2*n][n][0] && !dp[2*n][n][1]) {
cout << -1 << '\n';
} else {
ar<int, 3> curr = { -1, -1, -1 };
if(dp[2*n][n][0]) curr = { 2*n, n, 0 };
else curr = { 2*n, n, 1 };
string ans = "";
while(curr[0] != -1) {
auto [i, j, k] = curr;
if(k == 0) ans += 'A';
else ans += 'B';
curr = par[i][j][k];
}
reverse(ans.begin(), ans.end());
cout << ans << '\n';
}
}
