#include<stdio.h>
#include<math.h>
int main ()
{
    long long y,x,c,k;
    int n,i;
    scanf("%d", &n);
    for(i=1;i<=n;i++)
    {
        c=0;
       scanf("%lld %lld", &x, &y);
       if(x%3==0)
       {
           x=x+1;
           c++;
       }
       else if(x%3==2)
       {
           x=x+2;
           c=c+2;
       }
       else
       {
           x=x;
       }
       if(y%3==1)
       {
           y=y-1;
       }
       else if(y%3==2)
       {
           y=y-2;
           c=c+1;
       }
       else
       {
           y=y;
       }
       k=((y-x+1)*2)/3;
       c=c+k;
       printf("Case %d: %lld\n",i ,c);
    }
    return 0;
}