void main(){
  import std.stdio, std.string, std.conv, std.algorithm;

  int n; rd(n);
  auto a=readln.split.to!(long[]);

  auto s=reduce!("a+b")(a);
  if(s%2==0){writeln("B"); return;}

  auto c3=reduce!((res, e)=>res+(e>=3))(0, a);
  if(c3>0){writeln("B"); return;}
  auto c2=reduce!((res, e)=>res+(e==2))(0, a);
  if(c2>1) writeln("B");
  else writeln("A");
}

void rd(T...)(ref T x){
  import std.stdio, std.string, std.conv;
  auto l=readln.split;
  foreach(i, ref e; x){
    e=l[i].to!(typeof(e));
  }
}