#include <bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
#define pi pair <int, int>
#define pii pair <int, pi>
int n, A[1000005], B[1000005], memo[1000005][2], memo2[1000005][2];
int dp1(int x, int f){
if(x == 2 * n)return !f;
if(memo[x][f] != -1)return memo[x][f];
int val = (!f ? A[x] : B[x]);
int tmp = 1e18;
if(A[x + 1] >= val)tmp = min(tmp, dp1(x + 1, 0));
if(B[x + 1] >= val)tmp = min(tmp, dp1(x + 1, 1));
if(!f)tmp++;
return memo[x][f] = tmp;
}
int dp2(int x, int f){
if(x == 2 * n)return !f;
if(memo2[x][f] != -1)return memo2[x][f];
int val = (!f ? A[x] : B[x]);
int tmp = -1e18;
if(A[x + 1] >= val)tmp = max(tmp, dp2(x + 1, 0));
if(B[x + 1] >= val)tmp = max(tmp, dp2(x + 1, 1));
if(!f)tmp++;
return memo2[x][f] = tmp;
}
void solve(){
cin >> n;
for(int i = 1; i <= 2 * n; i++)cin >> A[i];
for(int i = 1; i <= 2 * n; i++)cin >> B[i];
memset(memo, -1, sizeof(memo));
memset(memo2, -1, sizeof(memo2));
string s;
int cura = 0, curb = 0, prv = 0;
for(int i = 1; i <= 2 * n; i++){
int mn = dp1(i, 0), mx = dp2(i, 0);
//cerr << mn << ' ' << mx << ' ';
if(mn <= n - cura && mx >= n - cura && A[i] >= prv){
s += 'A';
cura++;
prv = A[i];
}
else{
mn = dp1(i, 1), mx = dp2(i, 1);
//cerr << mn << ' ' << mx << ' ';
if(mn <= n - cura && mx >= n - cura && B[i] >= prv){
s += 'B';
curb++;
prv = B[i];
}
else{
cout << -1 << '\n';
return;
}
}
//cerr << s << '\n';
}
cout << s;
}
main(){
ios::sync_with_stdio(0);cin.tie(0);
int tc = 1;
//cin >> tc;
while(tc--)solve();
}
