#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
#define ll long long
#define int long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<pii, int> ipii;
const int MAXN = 5e3+20;
const int MAXA = 9e3+20;
const ll INF = 1e18+10;
const int LOG = 19;
const int MOD = 1e9+7;
const int SQRT = 450;
const vector<int> NOL = {};
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const vector<int> dx = {1, -1, 0, 0};
const vector<int> dy = {0, 0, 1, -1};
void chmx(int &a, int b){
a = max(a, b);
}
int n;
int a[MAXN], b[MAXN];
pii dp[MAXN][MAXN][2];
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] = {1, -1};
for(int i=1; i<=2*n; i++){ // idx
for(int l=0; l<=i; l++){
// dp[l][r][0] -> terakhir a
int r = i-l;
if(l!=0){ // ambil a
if(a[l-1+r] <= a[i] && dp[l-1][r][0].fi)
dp[l][r][0] = {1, 0};
if(b[l-1+r] <= a[i] && dp[l-1][r][1].fi)
dp[l][r][0] = {1, 1};
}
if(r!=0){ // ambil b
if(a[l-1+r] <= b[i] && dp[l][r-1][0].fi)
dp[l][r][1] = {1, 0};
if(b[l-1+r] <= b[i] && dp[l][r-1][1].fi)
dp[l][r][1] = {1, 1};
}
}
}
pii ANS = max(dp[n][n][0], dp[n][n][1]);
if(ANS.fi == 0){ cout << "-1\n"; return 0; }
string ret = "";
int l=n, r=n, idx = (dp[n][n][0].fi < dp[n][n][1].fi);
while(l!=0 || r!=0){
ret += (idx ? 'B' : 'A');
if(dp[l][r][idx].se==0){
if(idx==1) r--;
else l--;
idx = 0;
} else {
if(idx==1) r--;
else l--;
idx = 1;
}
}
reverse(ret.begin(), ret.end());
cout << ret << '\n';
}
/*
2
3 4 5 6
10 9 8 7
*/
