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

shw = [list(map(str, input())) for _ in range(W)]

        

for i in range(1,H-1):
    for j in range(1,W-1):
        if shw[i][j] == str('#'):
            if shw[i][j] != shw[i+1][j] and shw[i][j] != shw[i][j+1] and shw[i][j] != shw[i-1][j] and shw[i][j] != shw[i][j-1]:
                print("No")
                exit()
print("Yes")