void tarjan(int x)
{ 
  dfn[x]=low[x]=++num; 
  s[++p]=x,v[x]=1; 
  for(int i=head[x];i;i=next[i])  
  if(!dfn[ver[i]])  
  {   
    tarjan(ver[i]);   
    low[x]=min(low[x],low[ver[i]]);  
  }  
  else 
    if(v[ver[i]]) low[x]=min(low[x],dfn[ver[i]]);
 if(low[x]==dfn[x])
 {
   int y; ++t;  
    do{y=s[p--],v[y]=0; c[y]=t;}while(y!=x); 
  }
}