var
  l,r,i,j,x,n,k,time,ans:longint;
  s,a:array[0..200000,0..40]of longint;
  b:array[0..200000]of longint;

procedure er(k,x:longint);
var
  i:longint;
begin
  while x>0 do
  begin
    inc(i);
    a[k,i]:=x mod 2;
    x:=x div 2;
  end;
end;

function yes:boolean;
var
  i:longint;
begin
  for i:=2 to k do
  if b[i]<>b[i-1] then yes:=false
  else yes:=true;
end;

begin
  assign(input,'balline.in'); reset(input);
  assign(output,'balline.out'); rewrite(output);
  readln(n,k);
  for i:=1 to n do
  begin
    read(x);
    er(i,x);
  end;
  if n=1 then
  begin
    writeln(0);
    close(input);
    close(output);
    halt;
  end;
  for i:=1 to n do
   for j:=1 to k do
   s[i,j]:=s[i-1,j]+a[i,j];

  r:=0;
  for l:=0 to n-1 do
  begin
    for i:=n downto r do
    begin
      for j:=1 to k do
      b[j]:=s[i,j]-s[l,j];
      if yes then break;
    end;
    r:=i;
    if r-l>ans then ans:=r-l;
    inc(r);
  end;
  writeln(ans);
  close(input);
  close(output);
end.