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

#include<cstdio>

#include<cstring>

#include<cstdlib>

#include<algorithm>

#include<iostream>

#include<sstream>

#include<cmath>

#include<climits>

#include<string>

#include<map>

#include<queue>

#include<vector>

#include<stack>

#include<set>

using namespace std;

typedef long long ll;

typedef unsigned long long ull;

typedef pair<int,int> pii;

#define pb(a) push(a)

#define INF 0x1f1f1f1f

#define lson idx<<1,l,mid

#define rson idx<<1|1,mid+1,r

#define PI  3.1415926535898

template<class T> T min(const T& a,const T& b,const T& c) {

    return min(min(a,b),min(a,c));

}

template<class T> T max(const T& a,const T& b,const T& c) {

    return max(max(a,b),max(a,c));

}

void debug() {

#ifdef ONLINE_JUDGE

#else

    freopen("data.in","r",stdin);

   // freopen("d:\\out1.txt","w",stdout);

#endif

}

int getch() {

    int ch;

    while((ch=getchar())!=EOF) {

        if(ch!=' '&&ch!='\n')return ch;

    }

    return EOF;

}

const int maxn = ;

vector<int> g[maxn];

int n, m;

void Init()

{

     for(int i=; i<=n; i++)

          g[i].clear();

}

void add(int u, int v)

{

     g[u].push_back(v);

}

int match[maxn];

int vis[maxn];

bool dfs(int u)

{

     vis[u] = true;

     for(int i = ; i < g[u].size(); i++)

     {

          int v = g[u][i];

          int w = match[v];

          if(w<||!vis[w]&&dfs(w))

          {

               match[u] = v;

               match[v] = u;

               return true;

          }

     }

     return false;

}

int solve()

{

     memset(match,-,sizeof(match));

     int res = ;

     for(int u=; u <= n; u++)

     {

          if(match[u]<)

          {

               memset(vis, , sizeof(vis));

               if(dfs(u))

                    res++;

          }

     }

     return res;

}

int main()

{

     debug();

     while(scanf("%d%d", &n, &m) != EOF)

     {

          for(int i=; i<=m; i++)

          {

               int u,v;

               scanf("%d%d", &u, &v);

               add(u, v+n);

               add(v+n, u);

          }

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

     }

     return ;

}