import std.algorithm, std.container, std.conv, std.math, std.range, std.typecons, std.stdio, std.string;

auto rdsp(){return readln.splitter;}
void pick(R,T)(ref R r,ref T t){t=r.front.to!T;r.popFront;}
void readV(T...)(ref T t){auto r=rdsp;foreach(ref v;t)pick(r,v);}
void readC(T...)(size_t n,ref T t){foreach(ref v;t)v=new typeof(v)(n);foreach(i;0..n){auto r=rdsp;foreach(ref v;t)pick(r,v[i]);}}

void main()
{
  int n, k; readV(n, k);
  int[] h; readC(n, h);

  h.sort();

  auto r = 10^^9;
  foreach (i; 0..n-k+1)
    r = min(r, h[i+k-1]-h[i]);

  writeln(r);
}
