h, w = map(int, input().split())
s = [list(input()) for i in range(h)]
output = "Yes"

for i in range(1, w - 1):
    for k in range(1, h - 1):
        if s[i - 1][k] == "." and s[i + 1][k] == "." and s[i][k - 1] == "." and s[i][k + 1] == ".":
            output = "No"
            break

    else:
        break
    continue

print(output)
