program task_b;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  n,k,i:longint;
  d:array[1..1000000] of int64;
  f:text;
  min:int64;

  procedure QSort(l,r:longint);
  var
  buf:int64;
  key,i,j:longint;
  begin
  if (l<r) then
  begin
  i:=l;
  j:=r;
  key:=d[(i+j) div 2];
  while (i<j) do
  begin
  while (d[i]<key) do inc(i);
  while (d[j]>key) do dec(j);
  if (i<=j) then
  begin
  buf:=d[i];
  d[i]:=d[j];
  d[j]:=buf;
  inc(i);
  dec(j);
  end;
  end;
  QSort(l,j);
  QSort(i,r);
  end;

  end;

begin
assign(f,'holy.in');
reset(f);
readln(f,n,k);
for i:=1 to n do read(f,d[i]);
close(f);
QSort(1,n);
//for i:=1 to n do write(d[i],' ');
//readln;
min:=1000000001;
for i:=1 to n do
begin
if ((i+k-1)>n)  then break;
if (min>(d[i+k-1]-d[i])) then min:=d[i+k-1]-d[i];
end;


assign(f,'holy.out');
rewrite(f);
writeln(f,min);

close(f);
  { TODO -oUser -cConsole Main : Insert code here }
end.