#include <iostream>

using namespace std;

int t, n;

int main() {
    // freopen("game.in", "r", stdin);
    // freopen("game.out", "w", stdout);
    
    scanf("%d", &n);
    int cnt1 = 0, cnt2 = 0, cnt3 = 0;
    for (int i = 1, x; i <= n; ++i) {
        scanf("%d", &x);
        if (x == 1) ++cnt1;
        else if (x == 2) ++cnt2;
        else ++cnt3;
    }

    if (cnt3 || cnt2 >= 2) puts("B");
    else {
        if (cnt2 == 1) cnt1 += 2;
        puts(cnt1 % 2 == 1 ? "A" : "B");
    }

    return 0;
}