POJ 1611 The Suspects

/***********************************
Problem: POJ 1611 The Suspects
Time: 16MS
Memory: 276K
Accepted Time: 2009-08-19 20:26:36
Tip:  并查集 http://hi.baidu.com/fandywang_jlu/blog/item/b49e40893ddbb0b00f244485.html ************************************/
#include <stdio.h>
int pre[30000];
void Init(int n)
{
for(int i=0;i<n;i++)pre[i]=-1;
}
int Find(int x)
{
int p=x;
while(pre[p]>0)p=pre[p];
while(p!=x)
{
int temp=pre[x];
pre[x]=p;
x=temp;
}
return x;
}
void Union(int x,int y)
{
int a=Find(x),b=Find(y);
if(a==b)return;
if(pre[a]<pre[b])pre[a]+=pre[b],pre[b]=a;
else pre[b]+=pre[a],pre[a]=b;
}
int main()
{
int n,m;
while(scanf("%d%d",&n,&m),n+m!=0)
{
if(m==0)
{
printf("1/n");
continue;
}
Init(n);
int i,n2,t1,t2;
while(m--)
{
scanf("%d",&n2);
scanf("%d",&t1);
for(i=1;i<n2;i++)
{
scanf("%d",&t2);
Union(t1,t2);
}
}
printf("%d/n",-pre[Find(0)]);
}
return 0;
}