h, w = map(int, input().split())
list_S = [ list(input()) for _ in range(h) ]
ans = "Yes"
a = 0
for i in range(h):
    for j in range(w):
        cnt = 0
        if list_S[i][j] != "#":
            break
        a += 1
        if i + 1 >= 0 and i + 1< h and j >= 0 and j < w:
            if list_S[i+1][j] == "#":
                cnt += 1

        if i - 1 >= 0 and i - 1< h and j >= 0 and j < w:
            if list_S[i-1][j] == "#":
                cnt += 1

        if i >= 0 and i < h and j + 1 >= 0 and j + 1 < w:
            if list_S[i][j+1] == "#":
                cnt += 1

        if i >= 0 and i < h and j - 1>= 0 and j - 1 < w:
            if list_S[i][j-1] == "#":
                cnt += 1
        if cnt == 0:
            ans = "No"


if a == 1:
    ans = "Yes"


print(ans)
