import sys
h, w = map(int, input().split())
s = [list(input()) for _ in range(h)]
hantei = [[0 for _ in range(h)] for _ in range(w)]
for i in range(w-1):
    for j in range(h-1):
        if s[i][j] == "#":
            if s[i+1][j] == "#":
                hantei[i+1][j] = 1
                hantei[i][j] = 1
            if s[i][j+1] == "#":
                hantei[i][j+1] = 1
                hantei[i][j] = 1
for j in range(w-1):
    if s[h-1][j] == "#":
        if s[h-1][j+1] == "#":
            hantei[h-1][j] = 1
            hantei[h-1][j+1] = 1
for i in range(h-1):
    if s[i][w-1] == "#":
        if s[i+1][w-1] == "#":
            hantei[i][w-1] = 1
            hantei[i+1][w-1] = 1


for i in range(w):
    for j in range(h):
        if s[i][j] == "#":
            if hantei[i][j] == 0:
                print("No")
                sys.exit()

print("Yes")