#include <iostream>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <string>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
using namespace std;

#define REP(i,n) for(int i=0; i<n; ++i)
#define FOR(i,a,b) for(int i=a; i<=b; ++i)
#define FORR(i,a,b) for (int i=a; i>=b; --i)
#define ALL(c) (c).begin(), (c).end()

typedef long long ll;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef vector<VI> VVI;
typedef pair<int,int> P;
typedef pair<ll,ll> PL;

int main() {
    int n;
    cin >> n;
    int one = 0, two = 0, three = 0;
    REP(i,n){
        int x;
        cin >> x;
        if (x == 1) one ^= 1;
        if (x == 2) two++;
        if (x >= 3) three++;
    }

    bool a = false;

    if (one && ((two == 1 && !three) || (two + three == 0))) a = true;

    cout << (a ? "A" : "B") << endl;

    return 0;
}