#include <stdio.h>
int main(){
int n,a[3],temp;
a[0]=a[1]=a[2]=0;
scanf("%d",&n);
for(int i=0;i<n;i++){
scanf("%d",&temp);
if(temp>2){
printf("B\n");
return 0;
}
else a[temp]++;
}
if(a[2]>1){
printf("B\n");
return 0;
}
if(a[1]%2==0){
printf("B\n");
return 0;
}
printf("A\n");
}