[poj2524]Ubiquitous Religions

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
const int MAXN = 100000 + 50;
int fa[MAXN],n,m,a,b;
void init(int n)
{
for(int i = 1;i <= n;i ++)
fa[i] = i;
}
int find(int x)
{
return fa[x] == x ? x : fa[x] = find(fa[x]);
}
void merge(int a,int b)
{
a = find(a);
b = find(b);
fa[b] = a;
}
int cnt;
int main()
{
while(true)
{
cnt ++;
scanf("%d%d",&n,&m);
if(!n && !m)
{
return 0;
}
init(n);
for(int i = 1;i <= m;i ++)
{
scanf("%d%d",&a,&b);
merge(a,b);
}
int temp = n;
for(int i = 1;i <= n;i ++)
{
int t = find(i);
if(t != i)temp --;
}
printf("Case %d: %d\n",cnt,temp);
}
return 0;
}