program B;
var
        f:text;
        n,k,i,j:longint;
        d:array[1..100000] of int64;
        min:int64;
procedure Sort;
var
        ind,j,i:longint;
        byf:int64;
begin
        for i:=1 to n-1 do begin
                ind:=i;
                for j:=i+1 to n do
                        if d[j]>d[ind] then ind:=j;
                byf:=d[ind];
                d[ind]:=d[i];
                d[i]:=byf;
        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);
        assign(f,'holy.out');
        Sort;
        for i:=1 to n do write(d[i],' ');
        readln;
        min:=10000000000;
        for i:=1 to n-k do
                for j:=i+k-1 to n do
                        if d[i]-d[j]<min then min:=d[i]-d[j];
        writeln(min);
        readln;
end.