#include "bits/stdc++.h"
using namespace std;

#define DEBUG(x) cout<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cout<<#v<<":";for(int i=0;i<v.size();i++) cout<<" "<<v[i]; cout<<endl

typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
const int inf = 1000000001;
const ll INF = 1e18 * 4;
#define MOD 1000000007
#define mod 1000000009
#define pi 3.14159265358979323846
#define Sp(p) cout<<setprecision(15)<<fixed<<p<<endl;
int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };

int main() {
	int n, i, j;
	cin >> n;
	vl c;
	for (i = 0; i < n; i++) {
		int k;
		cin >> k;
		if (k == 0)
			continue;
		if (k >= 3) {
			cout << "B" << endl;
			return 0;
		}
		c.push_back(k);
	}
	n = c.size();
	int m = count(c.begin(), c.end(), 2);
	if (m == 0) {
		if (n % 2) {
			cout << "A" << endl;
		}
		else {
			cout << "B" << endl;
		}
	}
	else if (m == 1) {
		if (n % 2) {
			cout << "B" << endl;
		}
		else {
			cout << "A" << endl;
		}
	}
	else {
		cout << "B" << endl;
	}
}