#include<stdio.h>

int main()
{
  int a,b,x;
  scanf("%d%d%d",&x,&a,&b);
  {
      if(x-a>=0)
       a=x-a;
      else a=a-x;
      if(x-b>=0)
        b=x-b;
      else
        b=b-x;
      if(a<=b)
        printf("A\n");
      else printf("B\n");
  }
}
