/*
   ACM North Central Region, 1994-95
   Problem B, Rational Numbers from Repeating Fractions

   Ed Karrels, Ma	 1996
*/

#include <stdio.h>
#include <math.h>

int main() {
   double x, y;
   int k, j, i, a, b, c=1;

   scanf("%d %lf", &j, &x);
   while (j != -1) {
      y = x * pow(10, j);
      for (k=0; y != (double)((long)y); y*=10,k++);
      a = (int)(pow(10, k+j)*x) - (int)(pow(10,k)*x);
      b = pow(10, k+j) - pow(10,k);
      for (i=a<b ? a : b; a%i || b%i; i--);
      a/=i; b/=i;
      printf("Case %d: %d/%d\n", c++, a, b);
      scanf("%d %lf", &j, &x);
   }
   return 0;
}