# include <cstdio>

# include <cstring>

# include <cstdlib>

# include <iostream>

# include <vector>

# include <queue>

# include <stack>

# include <map>

# include <set>

# include <cmath>

# include <algorithm>

using namespace std;

# define lowbit(x) ((x)&(-x))

# define pi acos(-1.0)

# define eps 1e-

# define MOD

# define INF

# define mem(a,b) memset(a,b,sizeof(a))

# define FOR(i,a,n) for(int i=a; i<=n; ++i)

# define FO(i,a,n) for(int i=a; i<n; ++i)

# define bug puts("H");

# define lch p<<,l,mid

# define rch p<<|,mid+,r

# define mp make_pair

# define pb push_back

typedef pair<int,int> PII;

typedef vector<int> VI;

# pragma comment(linker, "/STACK:1024000000,1024000000")

typedef long long LL;

int Scan() {

    int res=, flag=;

    char ch;

    if((ch=getchar())=='-') flag=;

    else if(ch>=''&&ch<='') res=ch-'';

    while((ch=getchar())>=''&&ch<='')  res=res*+(ch-'');

    return flag?-res:res;

}

void Out(int a) {

    if(a<) {putchar('-'); a=-a;}

    if(a>=) Out(a/);

    putchar(a%+'');

}

const int N=;

//Code begin...

struct Edge{int p, next;}edge[N<<];

int head[N], cnt=, linker[N], uN;

bool used[N];

void add_edge(int u, int v){edge[cnt].p=v; edge[cnt].next=head[u]; head[u]=cnt++;}

bool dfs(int u){

    for (int i=head[u]; i; i=edge[i].next) {

        int v=edge[i].p;

        if (used[v]) continue;

        used[v]=true;

        if (linker[v]==-||dfs(linker[v])){linker[v]=u; return true;}

    }

    return false;

}

int hungary(){

    int res=;

    mem(linker,-);

    FO(u,,uN){

        mem(used,);

        if (dfs(u)) res++;

        else break;

    }

    return res;

}

int main ()

{

    int n, m, u, v;

    scanf("%d%d",&n,&m);

    uN=m;

    FO(i,,m) scanf("%d%d",&u,&v), add_edge(i,u), add_edge(i,v);

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

    return ;

}