#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll gcd(ll a,ll b)
{
   ll r;
   while (1)
   {
      r=a%b;
      if (r==0) return b;
      a=b;
      b=r;
   }
}
int main()
{
  string s,num;
  ll n,len,j,k,a,b,r,i=0,c,p,q;
  while(1)
  {
    getline(cin,num);
    stringstream ss(num);
    ss>>n;
    if (n==-1) break;
    ss>>s;
    len=s.size();
    k=len-2;
    k=k-n;
    a=0; p=1; b=0; q=1;
    for (j=2; j<len; j++)
    {
      a=(a*10)+(s[j]-'0');
      p=10*p;
      if(j-1==k)
      {
          b=a;
          q=p;
      }
    }
     if(n!=0) {a-=b; p-=q;}
    /* cout<<a<<" "<<p<<endl;*/
     r=gcd(a,p);
    printf("Case %lld: %lld/%lld\n",++i,a/r,p/r);
  }
 return 0;
}