#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include<vector>
#include<algorithm>
#include<math.h>
#include<cstring>
#include<map>
#include<set>
#include <cctype>
#include <cmath>
#include <cstdio>
#include<string>
using namespace std;

int gcd(int a, int b) {
	if (a == 0)
		return b;
	return gcd(b%a, a);
}

int main() {
	int n;
	string s;
	cin >> n;
	int k, a, b;
	double x;
	int css = 1;
	while (n != -1) {
		cin >> s;
		int size = s.size();
		int m = min(size-1, size - n);
		s += s.substr(m ,size);
		x = stod(s);

		k = size - 2 - n;

		b = pow(10, k + n) ;
		if (n != 0)
			b -= pow(10, k);
		a = pow(10, k + n)*x;
		if(n!=0)
			a-= (int)(pow(10, k)*x);
		int g = gcd(a, b);
		printf("Case %d: ", css); ++css;

		printf("%d/%d\n", a/g,b/g);
		cin >> n;
	}
	system("pause");
}