import std.stdio, std.string, std.conv, std.algorithm;
import std.range, std.array, std.math, std.typecons, std.container, core.bitop;


void main() {
    int n;
    int[] c;

    scan(n);
    c = readln.split.to!(int[]);

    c.sort!"a > b"();

    if (c[0] == 0) {
        writeln("B");
    }
    else {
        c[0]--;

        long cs = c.sum(0L);

        if (cs & 1) {
            writeln("B");
            return;
        }

        foreach (i ; 0 .. n) {
            if (c[i] >= 2) {
                writeln("B");
                return;
            }
        }

        writeln("A");
    }
}


void scan(T...)(ref T args) {
    string[] line = readln.split;
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}



void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}