#include<cstdio>

 #include<algorithm>

 #define N 1000050

 #define M 1000050

 const int inf =0x37373737;

 using namespace std;

 int n,m,i,a,b;

 struct Dinic {

     int s, t, n, pre[N], cur[N], h[N], level[N], sign, q[N];

     int cap[M], to[M], ne[M], flow, e;

     void liu(int u, int v, int w) {

         to[e] = v, ne[e] = h[u], cap[e] = w;

         h[u] = e++;

     }

     void link(int u, int v, int w) {

         liu(u, v, w);

         liu(v, u, );

     }

     void init(int n) {

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

             h[i] = -;

         e = ;

     }

     bool bfs() {

         int L = , R = ;

         fill(level, level + n, -);

         sign = q[R++] = t;

         level[t] = ;

         while (L < R && level[s] == -) {

             int c = q[L++];

             for (int k = h[c]; ~k; k = ne[k]) {

                 if (cap[k ^ ] >  && level[to[k]] == -)

                     level[to[k]] = level[c] + , q[R++] = to[k];

             }

         }

         return ~level[s];

     }

     void push() {

         int pl = inf, p, k;

         for (p = t; p != s; p = to[k ^ ]) {

             k = pre[p];

             pl = min(pl, cap[k]);

         }

         for (p = t; p != s; p = to[k ^ ]) {

             k = pre[p];

             cap[k] -= pl;

             cap[k ^ ] += pl;

             if (cap[k] == )

                 sign = to[k ^ ];

         }

         flow += pl;

     }

     void dfs(int c) {

         if (c == t)

             push();

         else {

             for (int &k = cur[c]; ~k; k = ne[k])

                 if (cap[k] >  && level[to[k]] +  == level[c]) {

                     pre[to[k]] = k;

                     dfs(to[k]);

                     if (level[sign] > level[c])

                         return;

                     sign = t;

                 }

             level[c] = -;

         }

     }

     int run(int _s, int _t, int _n) {

         s = _s, t = _t, n = _n;

         flow = ;

         while (bfs()) {

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

                 cur[i] = h[i];

             dfs(s);

         }

         return flow;

     }

 } mf;

 int main()

 {

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

     mf.init(*n+m+);

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

     mf.link(,i,),mf.link(n+i,*n+m+,);

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

     {

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

         mf.link(a,*n+i,);

         mf.link(*n+i,n+b,);

     }

     printf("%d\n",mf.run(,*n+m+,*n+m+));

 }