foo.cpp: In member function 'void Graph::dfs(int, int, int)':
foo.cpp:25:28: error: 'bn' was not declared in this scope
    vis[u]=1; dis[u]=l; bmn[bn]=min(bmn[bn],l); bmx[bn]=max(bmx[bn],l);
                            ^
foo.cpp: In member function 'void Graph::work()':
foo.cpp:49:40: error: 'bn' was not declared in this scope
    for(int i=1;i<=n;i++) if(vis[i]==0) bn++,dfs(i,-10,0);
                                        ^
foo.cpp:53:20: error: 'bn' was not declared in this scope
     for(int i=1;i<=bn;i++) ans+=(bmx[i]-bmn[i]+1);
                    ^