program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;

type mas=array[1..100000]of longint;


procedure swap(var a,b:longint);
var x:longint;
begin
x:=a;
a:=b;
b:=x;
end;


function partition(var A:mas;p,r:longint):longint;
var x,i,j:longint;
begin
  x:=A[r];
  i:=0;
  for j:=p to r-1 do
  if A[j]<=x then begin inc(i); swap(A[i],A[j]); end;
  swap(A[i+1],A[r]);
  partition:=i+1;
end;



procedure qsort(var A:mas;p,r:longint);
var q:longint;
begin
if p<r then
begin
q:=partition(A,p,r);
qsort(A,p,q-1);
qsort(A,q+1,r);
end;
end;


function max(a,b:longint):longint;
begin
if a>b then max:=a else max:=b;
end;

var n,k,i,min,ri,l,kn,res:longint;
d,r:mas;
begin
res:=0;
assign(input,'holy.in');
reset(input);
read(n,k);
for i:=1 to n do
begin
read(d[i]);
end;
close(input);

qsort(d,1,n);
min:=1;
{vmax:=1; }
for i:=2 to n do
begin
r[i-1]:=abs(d[i]-d[i-1]);
if r[i-1]<r[min] then min:=i-1;
end;
l:=min;
ri:=min+1;
kn:=2;
while kn<>k do
begin
if ((r[l-1]>=r[ri])and(ri<n-1))or(l<2)then
begin inc(ri);
{if r[ri-1]<r[min] then min:=ri-1;
if r[ri-1]>r[vmax] then vmax:=ri-1;}
end else
if l>1 then
begin dec(l);
{min:=l;
if r[l]<r[min]then min:=l;
if r[l]>r[vmax]then vmax:=l}
end;
inc(kn);
end;

{res:=d[vmax]-d[min]; }
res:=d[ri]-d[l];

assign(output,'holy.out');
rewrite(output);
writeln(res);
close(output);
end.