type node=record

        po,len,next:longint;

      end;

 var w:array[..] of node;

     f,p1,p2,p:array[..] of longint;

     v:array[..] of boolean;

     i,ans,loc,maxx,t,n,k,x,y:longint;

 function max(a,b:longint):longint;

   begin

     if a>b then exit(a) else exit(b);

   end;

 procedure add(x,y:longint);

   begin

     inc(t);

     w[t].po:=y;

     w[t].len:=;

     w[t].next:=p[x];

     p[x]:=t;

   end;

 procedure dfs(x:longint);

   var i,y,s1,s2:longint;

   begin

     i:=p[x];

     v[x]:=true;

     s1:=;

     s2:=;

     while i<>- do

     begin

       y:=w[i].po;

       if not v[y] then

       begin

         dfs(y);

         if f[y]+w[i].len>s1 then

         begin

           s2:=s1;

           p2[x]:=p1[x];

           s1:=f[y]+w[i].len;

           p1[x]:=i;

         end

         else if (s2<f[y]+w[i].len) then

         begin

           s2:=f[y]+w[i].len;

           p2[x]:=i;

         end;

       end;

       i:=w[i].next;

     end;

  //   writeln(x,' ',s1,' ',s2);

     f[x]:=s1;

     if maxx<s1+s2 then

     begin

       maxx:=s1+s2;

       loc:=x;

     end;

   end;

 begin

   t:=-;

   fillchar(p,sizeof(p),);

   fillchar(p1,sizeof(p1),);

   fillchar(p2,sizeof(p2),);

   readln(n,k);

   for i:= to n- do

   begin

     readln(x,y);

     add(x,y);

     add(y,x);

   end;

   dfs();

   ans:=*(n-)-maxx+;

   if k= then

   begin

     maxx:=;

     w[p1[loc]].len:=-;

     w[p2[loc]].len:=-;

     x:=w[p1[loc]].po;

     while p1[x]<>- do

     begin

       w[p1[x]].len:=-;

       x:=w[p1[x]].po;

     end;

     x:=w[p2[loc]].po;

     while p1[x]<>- do

     begin

       w[p1[x]].len:=-;

       x:=w[p1[x]].po;

     end;

     fillchar(v,sizeof(v),false);

     fillchar(f,sizeof(f),);

     dfs();

     ans:=ans-maxx+;

   end;

   writeln(ans);

 end.