import std;

alias sread = () => readln.chomp();
alias lread = () => readln.chomp.to!long();
alias aryread(T = long) = () => readln.split.to!(T[]);
//aryread!string();
//auto PS = new Tuple!(long,string)[](M);
//x[]=1;でlong[]全要素1に初期化
void main()
{
    long n, k;
    scan(n, k);
    auto h = new long[](n);
    foreach (i; 0 .. n)
    {
        auto H = lread();
        h[i] = H;
    }
    // writeln(h);
    h.sort();
    long ans = long.max;
    foreach (i; 0 .. ((n - k) + 1))
    {
        // writeln(h[i .. i + k]);
        ans = min(ans, (h[(i + k) - 1] - h[i]));
    }
    writeln(ans);
}

void scan(L...)(ref L A)
{
    auto l = readln.split;
    foreach (i, T; L)
    {
        A[i] = l[i].to!T;
    }
}

void arywrite(T)(T a)
{
    a.map!text.join(' ').writeln;
}
