program main
  implicit none
  integer::N,i,j,M
  character*14::a
  integer::days(14)
  integer::days2(14)
  data days/14*0/
  read *,N
  read *,a(1:7)
  read *,a(8:14)

  do i=1,14
     if(a(i:i).eq.'o') days(i) = 1
  end do

  M = 0

  do i=1,14-N+1
     days2 = days
     days2(i:i+N-1) = 1
     M = MAX(M,get_longest(days2))
  end do

  print '(i0)', M
contains
  function get_longest(days2) result(L)
    integer::days2(14),L,M
    integer::i
    L = 0
    M = 0
    do i=1,14
       if(days2(i).eq.1) then
          M = M + 1
       else
          L = MAX(L,M)
          M = 0
       end if
    end do
    L = MAX(L,M)

  end function get_longest
end program main