POJ-2524-Ubiquitous Religions

#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
const int maxn=50010;
int n,m,p[maxn];
int find(int x)
{
if(p[x]==-1)
return x;
return p[x]=find(p[x]);
}
int main()
{
int cas=1;
while(scanf("%d%d",&n,&m)&&(n+m))
{
memset(p,-1,sizeof(p));
for(int i=0;i<m;i++)
{
int ita,itb;
scanf("%d%d",&ita,&itb);
int x=find(ita);
int y=find(itb);
if(x!=y)
{
p[x]=y;
n--;
}
}
printf("Case %d: %d\n",cas++,n);
}
return 0;
}