1 #include<iostream>
 2 #include<cstring>
 3 #include<queue>
 4 #include<cstdio>
 5 #define maxn 10001
 6 using namespace std;
 7 struct data{int v,next,c;}e[maxn*2+10];
 8 int n,m,max1=1e9,ans,tot,cnt=1,dep[maxn],head[maxn];
 9 inline int read(){
10     int x=0,f=1;char ch=getchar();
11     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
12     while(ch>=‘0‘&&ch<=‘9‘) x=x*10+ch-48,ch=getchar();
13     return x*f;
14 }
15 void add(int u,int v,int x){
16     e[++cnt].v=v;e[cnt].c=x;
17     e[cnt].next=head[u];head[u]=cnt;
18 }
19 bool BFS(){
20     memset(dep,-1,sizeof dep );
21     queue<int>q;q.push(0);dep[0]=0;
22     while(!q.empty()){
23         int u=q.front();q.pop();
24         for(int i=head[u];i;i=e[i].next){
25             int v=e[i].v;
26             if(dep[v]==-1&&e[i].c){
27                 dep[v]=dep[u]+1;
28                 if(v==n+1)return true;
29                 else q.push(v);
30             }
31         }
32     }
33     return dep[n+1]!=-1;
34 }
35 int dfs(int u,int y){
36     if(u==n+1)return y;
37     int ret=0;
38     for(int i=head[u];i;i=e[i].next){
39         int v=e[i].v;
40         if(dep[v]==dep[u]+1&&e[i].c){
41             int x=dfs(v,min(y-ret,e[i].c));
42             ret+=x;
43             e[i].c-=x;
44             e[i^1].c+=x;
45         }
46     }
47     if(!ret)dep[u]=-1;
48     return ret;
49 }
50 void Dinic(int s,int t){
51     while(BFS())ans+=dfs(s,max1);
52     printf("%d\n",ans);
53     return ;
54 }
55 int main(){
56     freopen("flyer.in","r",stdin);
57     freopen("flyer.out","w",stdout);
58     int x,y;
59     n=read();m=read();
60     for(int i=1;i<=m;i++)add(0,i,1),add(i,0,0);
61     for(int i=m+1;i<=n;i++)add(i,n+1,1),add(n+1,i,0);
62     while(scanf("%d%d",&x,&y)!=EOF)
63         add(x,y,max1),add(y,x,0);
64     Dinic(0,n+1);
65     return 0;
66 }