program jifang;
var
  n,m,i,j,d1,d2:longint;
  one,two,f,a:array[0..2500]of longint;
begin
  assign (input,'orz.in');
  reset (input);
  assign (output,'orz.out');
  rewrite (output);
    readln(n,m);
    for i:=1 to n do
    begin
      readln(a[i]);
      if a[i]=1 then
      begin
        one[i]:=one[i-1]+1;
        two[i]:=two[i-1]
      end
      else
      begin
        one[i]:=one[i-1];
        two[i]:=two[i-1]+1
      end
    end;
    for i:=1 to n do
      f[i]:=maxlongint;
    f[0]:=0;
    for i:=1 to n do
      for j:=1 to i do
      begin
        d1:=one[i]-one[j-1];
        d2:=two[i]-two[j-1];
        if (d1=0)or(d2=0)or(abs(d1-d2)<=m) then
          if f[j-1]+1<f[i] then
            f[i]:=f[j-1]+1
      end;
    writeln(f[n]);
  close (input);
  close (output)
end.