#include <cstring>
#include <string>
#include <queue>
#include <cstdio>
using namespace std;
int fa[50005];
int findd(int x)
{
if(x==fa[x])return x;
return fa[x]=findd(fa[x]);
}
int main()
{
int n,m;
int r=1;
while(~scanf("%d%d",&n,&m))
{
if(n+m==0)break;
int sum=n;
for(int i=0;i<=n;i++)fa[i]=i;
while(m--)
{
int x,y;
scanf("%d%d",&x,&y);
int fx=findd(x);
int fy=findd(y);
if(fx!=fy){
fa[fy]=fx;//合併兩棵樹
sum--;
}
}
printf("Case %d: %d\n",r++,sum);
}
return 0;
}