Ice_cream's world I

ice_cream's world is a rich country, it has many fertile lands. Today, the queen of ice_cream wants award land to diligent ACMers. So there are some watchtowers are set up, and wall between watchtowers be build, in order to partition the ice_cream’s world. But how many ACMers at most can be awarded by the queen is a big problem. One wall-surrounded land must be given to only one ACMer and no walls are crossed, if you can help the queen solve this problem, you will be get a land.

Input

In the case, first two integers N, M (N<=1000, M<=10000) is represent the number of watchtower and the number of wall. The watchtower numbered from 0 to N-1. Next following M lines, every line contain two integers A, B mean between A and B has a wall(A and B are distinct). Terminate by end of file.

Output

Output the maximum number of ACMers who will be awarded. 
One answer one line.

Sample Input

8 10
0 1
1 2
1 3
2 4
3 4
0 5
5 6
6 7
3 6
4 7

Sample Output

3

题意：就是分土地，被圈住的一块只能分给一个人，问做多能分给几个人。

思路：这题比较水，就看有多少个小圈就好了。

代码:

#include<stdio.h>
#include<string.h>

int f[1005],n,m;

int getf(int v)
{
    if(f[v]==v) return v;
    else {
        f[v]=getf(f[v]);
        return f[v];
    }
}

void merge(int u,int v)
{
    int t1,t2;
    t1=getf(u);
    t2=getf(v);
    if(t1!=t2)
    {
        f[t2]=t1;
    }
}

int main()
{
    while(~scanf("%d %d",&n,&m))
    {
        for(int i=0;i<=n;i++)
            f[i]=i;
        int x,y,sum=0;
        for(int i=1;i<=m;i++)
        {
            scanf("%d %d",&x,&y);
            if(getf(x)==getf(y))
                sum++;
            merge(x,y);
        }
        printf("%d\n",sum);
    }
    return 0;
}