import sys



def main():

  input = sys.stdin.readline

  H, W = list(map(int, input().split()))

  A = [[0 for _ in range(W+2)] for _ in range(H+2)]

  for i in range(H):

    a = [0] + [int(c == '#') for c in input().strip()] + [0]

    A[i+1] = a

  

  ans = 'Yes'

  for i in range(H):

    for j in range(W):

      if A[i+1][j+1] == 1:

        u, d, r, l = A[i][j+1], A[i+2][j+1], A[i+1][j+2], A[i+1][j]

        if any([a == 1 for a in [u, d, r, l]]):

          continue

        else:

          ans = 'No'

          break

  print(ans)





if __name__ == '__main__':

  main()
import sys



def main():

  input = sys.stdin.readline

  H, W = list(map(int, input().split()))

  A = [[0 for _ in range(W+2)] for _ in range(H+2)]

  for i in range(H):

    a = [0] + [c == '#' for c in input().strip()] + [0]

    A[i+1] = a

  

  ans = 'Yes'

  for i in range(H):

    for j in range(W):

      if A[i+1][j+1] == 1:

        u, d, r, l = A[i][j+1], A[i+2][j+1], A[i+1][j+2], A[i+1][j]

        if any([u, d, r, l]):

          continue

        else:

          ans = 'No'

          break

  print(ans)





if __name__ == '__main__':

  main()

import sys


def main():
    input = sys.stdin.readline
    H, W = list(map(int, input().split()))
    A = [[0 for _ in range(W + 2)] for _ in range(H + 2)]
    for i in range(H):
        a = [0] + [int(c == "#") for c in input().strip()] + [0]
        A[i + 1] = a
    ans = "Yes"
    for i in range(H):
        for j in range(W):
            if A[i + 1][j + 1] == 1:
                u, d, r, l = A[i][j + 1], A[i + 2][j + 1], A[i + 1][j + 2], A[i + 1][j]
                if any([a == 1 for a in [u, d, r, l]]):
                    continue
                else:
                    ans = "No"
                    break
    print(ans)


if __name__ == "__main__":
    main()

import sys


def main():
    input = sys.stdin.readline
    H, W = list(map(int, input().split()))
    A = [[0 for _ in range(W + 2)] for _ in range(H + 2)]
    for i in range(H):
        a = [0] + [c == "#" for c in input().strip()] + [0]
        A[i + 1] = a
    ans = "Yes"
    for i in range(H):
        for j in range(W):
            if A[i + 1][j + 1] == 1:
                u, d, r, l = A[i][j + 1], A[i + 2][j + 1], A[i + 1][j + 2], A[i + 1][j]
                if any([u, d, r, l]):
                    continue
                else:
                    ans = "No"
                    break
    print(ans)


if __name__ == "__main__":
    main()

-        a = [0] + [int(c == "#") for c in input().strip()] + [0] +        a = [0] + [c == "#" for c in input().strip()] + [0] -                if any([a == 1 for a in [u, d, r, l]]): +                if any([u, d, r, l]):