And search: the suspects (find the number of people related to the nth person)

Severe acute respiratory syndrome (SARS), an atypical pneumonia of unknown aetiology, was recognized as a global threat in mid-March 2003. To minimize transmission to others, the best strategy is to separate the suspects from others.
In the Not-Spreading-Your-Sickness University (NSYSU), there are many student groups. Students in the same group intercommunicate with each other frequently, and a student may join several groups. To prevent the possible transmissions of SARS, the NSYSU collects the member lists of all student groups, and makes the following rule in their standard operation procedure (SOP).
Once a member in a group is a suspect, all members in the group are suspects.
However, they find that it is not easy to identify all the suspects when a student is recognized as a suspect. Your job is to write a program which finds all the suspects.

Input

The input file contains several cases. Each test case begins with two integers n and m in a line, where n is the number of students, and m is the number of groups. You may assume that 0 < n <= 30000 and 0 <= m <= 500. Every student is numbered by a unique integer between 0 and n−1, and initially student 0 is recognized as a suspect in all the cases. This line is followed by m member lists of the groups, one line per group. Each line begins with an integer k by itself representing the number of members in the group. Following the number of members, there are k integers representing the students in this group. All the integers in a line are separated by at least one space.
A case with n = 0 and m = 0 indicates the end of the input, and need not be processed.

Output

For each case, output the number of suspects in one line.

Examples ：

 

The question ：n personal , One person is infected SARS, Then people in his group will be infected SARS, It is known that 0 No. has been infected

Input ：‎ The input file contains multiple cases . Each test case takes two integers in a row n and m start , among n It's the number of students ,m It's the number of groups . You can assume 0 < n < = 30000,0 < = m < = 500. Each student is represented by a student between 0 and n−1 A unique integer number between , And the first students 0 In all cases, they are considered suspects . This line is followed by... Of the group m A list of members , One row per group . Each line is in an integer k start , It itself represents the number of members in the Group . After the number of members , Yes k An integer represents the students in this group . All integers in a row are separated by at least one space .‎
‎n = 0 And m = 0 The end of the input , No need to deal with .‎

Output ：‎ For each case , Output the number of suspects in one line .‎

#include<iostream>
#include<cstdio>
using namespace std;

const int N=30010;

int n,m;
int p[N];
int size[N];

int find(int x)
{
	if(p[x]!=x)
		p[x]=find(p[x]);
	return p[x];
}

void solve()
{
	for(int i=0;i<=n;i++)
	{
		p[i]=i;
		size[i]=1;
	}
	
	for(int i=1;i<=m;i++)
	{
		int t;
		scanf("%d",&t);
		int a[t+10];
		
		for(int j=0;j<t;j++)
			scanf("%d",&a[j]);
		
		for(int j=0;j<t-1;j++)
		{
			int x=find(a[j]);
			int y=find(a[j+1]);
			
			if(x==y)
				continue;
			
			p[y]=x;
			size[x]+=size[y];
		}
	}
	
	printf("%d\n",size[find(0)]);
}

int main()
{
	while(~scanf("%d%d",&n,&m)&&(m||n))
		solve();
	
	return 0;
}