#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;


int main(){
  int N;
  cin >> N;
  vector<int> v;
  rep(i,N){
    int a;
    cin >> a;
    if(a == 0) continue;
    v.push_back(a);
  }

  int n = 0;
  int m = 0;
  int l = 0;
  rep(i,v.size()){
    if(v[i] == 1){
      n++;
    }
    else if(v[i] == 2){
      m++;
    }
    else{
      l++;
    }
  }

  if((n%2==1 && m==0 && l==0) || n%2==1 && m==1 && l==0){
    cout << "A" << endl;
  }else{
    cout << "B" << endl;
  }

  
  return 0;
}