program Project1;
{$APPTYPE CONSOLE}
uses
  SysUtils;

var n,k,i,j,ans: longint;
    a: array[1..100000]of longint;
    inp,outp: text;
procedure qSort(var ar: array of longint; low,high: longint);
var i,j,wsp,m: longint;
begin
   i:=low;
   j:=high;
   m:=ar[(i+j)div 2];
   repeat
      while a[i]<m do inc(i);
      while a[j]>m do dec(j);
      if i<=j then
         begin
            wsp:=a[i];
            a[i]:=a[j];
            a[j]:=wsp;
            inc(i);
            dec(j);
         end;
   until i>j;
   if low<j then qSort(ar,low,j);
   if i<high then qSort(ar,i,high);
end;
begin
   assign(inp,'holy.in');
   assign(outp,'holy.out');
   reset(inp);
   rewrite(outp);
   readln(inp,n,k);
   for i:=1 to n do
      read(inp,a[i]);
   qSort(a,1,n);
   ans:=a[n]-a[n-k+1];
   for i:=n downto k do
      if a[i]-a[i-k+1]<ans then ans:=a[i]-a[i-k+1];

   {for i:=k+1 to n do
      if a[i]-a[1]<ans then ans:=a[i]-a[1];
   {for i:=1 to n do
      write(outp,a[i],' ');}
   writeln(outp,ans);
   close(inp);
   close(outp);
end.