#include<stdio.h>
int found(int a)
{
int res=a*2;
res=res/3;
res=(int)res;
   if(a%3==2||a%3==0)
     {

return res;
    }
else
   {
return res-1;
   }
}
int hresult(int a,int b)
  {
int top=found(b);
if(a%3 !=1)
  {
int min=found(a)-1;
   }
else
    {
int min=found(a);
    }
return top-min;
  }


int main(void)
{
int a,b,cases,caseno=0;
scanf("%d",&cases);
while(cases--)
{
scanf("%d %d",&a,&b);
// printf("%d %d\n",found(b),found(a));
 printf("Case %d: %d\n",++caseno,hresult(a,b));
}
return 0;
}