G - 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

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
int pre[1100];
int ans=0;
int n,m;
int u,v;

void init()
{
for(int i=0;i<n;i++)
{
pre[i]=i;
}
}
int find(int x)
{
if(pre[x]==x)
return x;
return pre[x]=find(pre[x]);
}
void mix(int x,int y)
{
int fx=find(x);
int fy=find(y);
if(fx!=fy)
{
pre[fy]=fx;
}
else
{
ans++;
}
}
int main()
{
while(~scanf("%d%d",&n,&m))
{
ans=0;
init();
for(int i=0;i<m;i++)
{
scanf("%d%d",&u,&v);
mix(u,v);
}
printf("%d\n",ans);
}
return 0;
}