1 #include <cstdio>
 2 #include <iostream>
 3 #define N 60010
 4 using namespace std;
 5 struct edge{int to,from;}e[N*3];
 6 int n,m,cnt=1,Fa[N],f[N][2],dfn[N],low[N],head[N];
 7 void insert(int x,int y)
 8 {
 9     e[++cnt].to=y,e[cnt].from=head[x],head[x]=cnt;
10     e[++cnt].to=x,e[cnt].from=head[y],head[y]=cnt;
11 }
12 void dp(int x,int y)
13 {
14     int r0,r1,f0=0,f1=0;
15     for (int i=y;i!=x;i=Fa[i]) r0=f0+f[i][0],r1=f1+f[i][1],f0=max(r0,r1),f1=r0;
16     f[x][0]+=f0,f0=0,f1=-1e9;
17     for (int i=y;i!=x;i=Fa[i]) r0=f0+f[i][0],r1=f1+f[i][1],f0=max(r0,r1),f1=r0;
18     f[x][1]+=f1;
19 }
20 void dfs(int x,int fa)
21 {
22     dfn[x]=low[x]=++dfn[0],f[x][1]=1,f[x][0]=0,Fa[x]=fa;
23     for (int i=head[x];i;i=e[i].from)
24     {
25         if (!dfn[e[i].to]) dfs(e[i].to,x),low[x]=min(low[x],low[e[i].to]); else if (e[i].to!=fa) low[x]=min(low[x],dfn[e[i].to]);
26         if (low[e[i].to]>dfn[x]) f[x][1]+=f[e[i].to][0],f[x][0]+=max(f[e[i].to][0],f[e[i].to][1]);
27     }
28     for (int i=head[x];i;i=e[i].from) if (Fa[e[i].to]!=x&&dfn[x]<dfn[e[i].to]) dp(x,e[i].to);
29 }
30 int main()
31 {
32     scanf("%d%d",&n,&m);
33     for (int i=1,x,y;i<=m;i++) scanf("%d%d",&x,&y),insert(x,y);
34     dfs(1,0),printf("%d",max(f[1][0],f[1][1]));
35 }