{$Mode objFPC}

type int = longint;
type bool = boolean;
type long = int64;

const MaxN = trunc(1e5);

function max(a, b: int): int; begin if a > b then exit(a); exit(b); end;
function min(a, b: int): int; begin if a < b then exit(a); exit(b); end;
function __gcd(a, b: int): int;
var r: int;
begin
    while b <> 0 do begin
        r:=a mod b;
        a:=b; b:=r;
    end;
    exit(abs(a));
end;

// Do có 1 loại cây thôi nên mình đặt luôn là Tree v: đỡ dài là chính v:
// Segment Tree
type iarray = array[0..MaxN * 4] of int;
type Tree = class
  private
    arr, f: iarray;
    size: int;
  public
    constructor Create();
    constructor Create(a: iarray; n: int);
    function merge(a, b: int): int;
    procedure build(l, r, id: int);
    function __get(u, v, l, r, id: int): int;
    function get(l, r: int): int;
end;

constructor Tree.Create();
begin
    size:=0;
    fillchar(f, sizeof(f), 0);
end;

constructor Tree.Create(a: iarray; n: int);
begin
    fillchar(f, sizeof(f), 0);
    size:=n;
    arr:=a;
    build(1, n, 1);
end;

function Tree.merge(a, b: int): int; begin exit(__gcd(a, b)); end;
procedure Tree.build(l, r, id: int); 
var mid, k: int;
begin
    if l = r then begin
        f[id]:=arr[l];
        exit;
    end;
    
    mid:=(l + r) shr 1; k:=id shl 1;
    build(l, mid, k);
    build(mid + 1, r, k or 1);
    f[id]:=merge(f[k], f[k or 1]);
end;

function Tree.__get(u, v, l, r, id: int): int;
var mid, k: int;
begin
    if (r < u) or (v < l) then exit(0);
    if (u <= l) and (r <= v) then exit(f[id]);
    mid:=(l + r) shr 1; k:=id shl 1;
    exit(merge(__get(u, v, l, mid, k), __get(u, v, mid + 1, r, k or 1)));
end;

function Tree.get(l, r: int): int;
begin
    exit(__get(l, r, 1, size, 1));
end;

var St: Tree;
var a: iarray;
var i, n, k: int;
var res: int;

begin
    readln(n, k);
    for i:=1 to n do read(a[i]);
    
    St:=Tree.Create(a, n);
    res:=0;
    for i:=1 to n - k + 1 do res:=max(res, St.get(i, i + k - 1));
    writeln(res);    
end.