h, w = map(int, input().split())
s = [input() for _ in range(h)]

for i in range(h):
    for j in range(w):
        flag = 1
        if i > 0:
            if s[i-1][j] == "#":
                flag = 0
        if i < h-1:
            if s[i+1][j] == "#":
                flag = 0
        if j > 0:
            if s[i][j-1] == "#":
                flag = 0
        if j < w-1:
            if s[i][j+1] == "#":
                flag = 0
        if flag == 1:
            print("No")
            exit()

print("Yes")