#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int INF = 1LL << 30;
int MOD = 1e9+7;
main(){
    int N;
    cin >> N;
    vector<int> A(N);
    for(int i = 0;i < N;i++)cin >> A[i];
    int ans = 0,cnt2 = 0,cnt1 = 0,flag = 0;
    for(int i = 0;i < N;i++){
        if(A[i] == 0) continue;
        if(A[i] == 1)      cnt1++;
        else if(A[i] == 2) cnt2++;
        else               flag = 1;
    }
    if(flag)ans = 0;
    else if(cnt2 == 1 && cnt1 & 1 == 1 || cnt2 == 0 && cnt1 & 1 == 1)ans = 1;
    else ans = 0;
    if(ans)cout << "A" << endl;
    else cout << "B" << endl;
}