4

1 2

3 4

5 6

1 6

4

1 2

3 4

5 6

7 8

4

2

Hint

A and B are friends(direct or indirect), B and C are friends(direct or indirect),

then A and C are also friends(indirect).

 In the first sample {1,2,5,6} is the result.

In the second sample {1,2},{3,4},{5,6},{7,8} are four kinds of answers.
 

#include<stdio.h>

#define max 10000000

int per[max+100];

int num[max+100];

int find(int x)//找根节点

{

	int r;

	r=x;

	while(r!=per[r])

	{

		r=per[r];

	}

	per[x]=r;

	return r;

}

void join(int x ,int y)//连接两根节点

{

	int fx=find(x);

	int fy=find(y);

	if(fx!=fy)

	{

		per[fx]=fy;

		num[fy]+=num[fx];//当前根节点的元素

	}

}

int main()

{

	int a,b,m,n,i;

	int t;

	while(~scanf("%d",&t))

	{

		if(t==0)

		{

			printf("1\n");

			continue;

		}

		for(i=1;i<=max;++i)//初始化

		{

			per[i]=i;

			num[i]=1;		//每一个节点仅仅有一个元素，自己本身

		}

		n=-1;//为了省时间，

		while(t--)

		{

			scanf("%d%d",&a,&b);

			if(a>n)

			{

				n=a;

			}

			if(b>n)

			{

				n=b;

			}

			join(a,b);

		}

		int MAX=0;

		for(i=1;i<=n;++i)//在这用上

		{

			if(MAX<num[i]) MAX=num[i];

		}

		printf("%d\n",MAX);

	}

	return 0;

}