1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 const int maxn=100+5,INF=0x7fffffff;
 5 int n,m,cnt=1;
 6 int lvl[maxn],itr[maxn],head[maxn];
 7 struct edge{
 8     int to,cap,next;
 9     edge(){}
10     edge(int to,int cap,int next):to(to),cap(cap),next(next){}
11 }g[maxn*maxn*2];
12 void add_edge(int u,int v,int cap){
13     g[++cnt]=edge(v,cap,head[u]); head[u]=cnt;
14     g[++cnt]=edge(u,0,head[v]); head[v]=cnt;
15 }
16 void bfs(int s){
17     memset(lvl,-1,sizeof lvl);
18     lvl[s]=0;
19     queue <int> q;
20     q.push(s);
21     while(!q.empty()){
22         int u=q.front(); q.pop();
23         for(int i=head[u];i;i=g[i].next){
24             int v=g[i].to;
25             if(lvl[v]<0&&g[i].cap>0){
26                 lvl[v]=lvl[u]+1;
27                 q.push(v);
28             }
29         }
30     }
31 }
32 int dfs(int u,int t,int f){
33     if(u==t) return f;
34     for(int &i=itr[u];i;i=g[i].next){
35         int v=g[i].to;
36         if(g[i].cap>0&&lvl[u]<lvl[v]){
37             int d=dfs(v,t,min(f,g[i].cap));
38             if(d>0){
39                 g[i].cap-=d;
40                 g[i^1].cap+=d;
41                 return d;
42             }
43         }
44     }
45     return 0;
46 }
47 int max_flow(int s,int t){
48     int flow=0;
49     for(bfs(s);lvl[t]>0;bfs(s)){
50         for(int i=0;i<=n+1;i++) itr[i]=head[i];
51         int f;
52         while((f=dfs(s,t,INF))>0) flow+=f;
53     }
54     return flow;
55 }
56 void init(){
57     scanf("%d%d",&n,&m);
58     for(int i=1;i<=m;i++) add_edge(0,i,1);
59     for(int i=m+1;i<=n;i++) add_edge(i,n+1,1);
60     int u,v;
61     while(scanf("%d%d",&u,&v)!=EOF) add_edge(u,v,1);
62 }
63 int main(){
64     freopen("flyer.in","r",stdin);
65     freopen("flyer.out","w",stdout);
66     init();
67     printf("%d\n",max_flow(0,n+1));
68     fclose(stdin);
69     fclose(stdout);
70     return 0;
71 }