program main
  implicit none
  integer(8) N, nd, ns, i, firsts, nd2,ans, finald, ns2
  !integer loc(4) loc2(4) !left ., left #, right ., right #
  character(2*(10**5)) S
  read(*, *) N
  read(*, *) S
  nd = 0
  ns = 0
  firsts = N
  finald = N
  ns2 = 0
  nd2 = 0
  do i = 1,N
    if (S(i:i) == '.') then
      nd = nd + 1
    else
      ns = ns + 1
    end if
  end do
  if (ns /= 0) then
    do i = 1,N
      if (S(i:i) == '#') then
        firsts = i
        exit
      end if
    end do
    do i = firsts,N
      if (S(i:i) == '.') then
        nd2 = nd2 + 1
      end if
    end do
  end if
  if (nd /= 0) then
    do i = 1,N
      if (S(i:i) == '.') then
        finald = i
      end if
    end do
    do i = 1,finald
      if (S(i:i) == '#') then
        ns2 = ns2 + 1
      end if
    end do
  end if
  
  ans = min(nd, ns, nd2, ns2)
  write(*,'(i0)') ans
end program main
