1 #include <algorithm>  2 #include <cstring>  3 #include <cstdio>  4   5 using namespace std;  6   7 const int N(100015);  8 int n,m,u,v;  9 int sumedge,head[N<<1]; 10 struct Edge 11 { 12     int to,next; 13     Edge(int to=0,int next=0) : 14         to(to),next(next) {} 15 }edge[N*5]; 16  17 void ins(int from,int to) 18 { 19     edge[++sumedge]=Edge(to,head[from]); 20     head[from]=sumedge; 21 } 22  23 int low[N<<1],dfn[N<<1],tim; 24 int sumcol,num[N]; 25 int cutpoint[N]; 26  27 void DFS(int now,int pre) 28 { 29     low[now]=dfn[now]=++tim; 30     int sumtredge=0,if_cutpoint=0; 31     for(int i=head[now];i!=-1;i=edge[i].next) 32     { 33         int go=edge[i].to; 34         if((go^1)!=pre) 35         { 36             if(!dfn[go]) 37             { 38                 sumtredge++; 39                 DFS(go,i); 40                 if(low[go]>=dfn[now]) 41                 { 42                     if_cutpoint=1; 43                     num[now]++; 44                 } 45                  46                 low[now]=min(low[now],low[go]); 47             } 48             else low[now]=min(low[now],dfn[go]); 49         } 50     } 51     if(pre==-1) 52     { 53         if(sumtredge>1)  cutpoint[now]=1; 54     } 55     else if(if_cutpoint) cutpoint[now]=1; 56 } 57  58 int ans,cnt,tmp,vis[N],root[N],cut[N]; 59  60 void link(int x) 61 { 62     vis[x]=1; 63     for(int i=head[x];i!=-1;i=edge[i].next) 64     { 65         v=edge[i].to; 66         if(!vis[v]) link(v); 67     } 68 } 69  70 void cut_point(int pre,int fa) 71 { 72     vis[pre]=1; 73     for(int i=head[pre];i!=-1;i=edge[i].next) 74     { 75         int go=edge[i].to; 76         if(!vis[go]) 77         { 78             if(pre==fa) cnt++; 79             cut_point(go,fa); 80         } 81     } 82 } 83  84 void init(int n) 85 { 86     sumedge=-1; ans=tim=tmp=cnt=0; 87     memset(vis,0,sizeof(vis)); 88     memset(low,0,sizeof(low)); 89     memset(dfn,0,sizeof(dfn)); 90     memset(num,0,sizeof(num)); 91     memset(cut,0,sizeof(cut)); 92     memset(root,0,sizeof(root)); 93     memset(head,-1,sizeof(head)); 94     memset(cutpoint,0,sizeof(cutpoint)); 95 } 96  97 int main() 98 { 99 //    freopen("makerout.txt","r",stdin);100 //    freopen("myout.txt","w",stdout);101     102     while(~scanf("%d%d",&n,&m)&&n)103     {104         init(n);105         if(m==0) printf("%d\n",n-1);106         else107         {108             for(;m;m--)    109             {110                 scanf("%d%d",&u,&v);111                 ins(u,v); ins(v,u);112             }113             for(int i=0;i<n;i++)114                 if(!vis[i]) ++tmp,link(i);115             for(int i=0;i<n;i++)116                 if(!dfn[i]) DFS(i,-1);117             for(int i=0;i<n;i++)118                 if(cutpoint[i])119                 {120                     memset(vis,0,sizeof(vis));121                     cut_point(i,i);122                     ans=max(ans,cnt-1);123                     cnt=0;124                 }125             ans+=tmp;126             printf("%d\n",ans);127         }128     }129     return 0;130 }