/**************************************************************

     Problem: 3093

     User: Tunix

     Language: C++

     Result: Accepted

     Time:0 ms

     Memory:804 kb

 ****************************************************************/

 //BZOJ 3093

 #include<cstdio>

 int main(){

     int n,p,q,t=;

     while(scanf("%d%d%d",&n,&p,&q)!=EOF)

         printf("Case %d: %.4f\n",++t,(q+1.0)/(p+2.0));

     return ;

 }