#include <iostream>

using namespace std;

int main(){
  int n;
  cin >> n;
  int res = 0;
  int r2 = 0;
  for(int i=0,a;i<n;i++){
    cin >> a;
    res |= a>2;
    r2 += a==2;
  }
  if(!res&&r2<2)cout << 'A' << endl;
  else cout << 'B' << endl;
}