#include <iostream>
#include <algorithm>
#include <stdlib.h>
#include <stdio.h>
int num;
using namespace std;

struct students
{
    int depth;
    int brief;
}student[50001];
int find(int x)
{
    if(student[x].brief!=x) student[x].brief=find(student[x].brief);
    return student[x].brief;
}
void merge(int p,int q)
{
    if(find(p)==find(q)) return;
    num--;
    student[q].brief=find(p);
}

int main()
{
    int n,m,i,j,time=1;
    while(1)
    {
        num=0;
        scanf("%d%d",&n,&m);
        if(n==0 && m==0) break;
        num=n;
        for(i=1;i<=n;i++)
        {
            student[i].brief=i;
        }
        while(m--)
        {
            scanf("%d%d",&i,&j);
            merge(i,j);
        }
        printf("Case %d:%d\n",time,num);
        time++;
    }
    return 0;
}