h,w = map(int,input().split())
s = [input() for i in range(h)]
ans = "Yes"
for i in range(h):
    for j in range(w):
        if s[i][j]=="#":
            a = ""
            b = ""
            if i==h-1:
                a = s[i-1][j]
            elif i==0:
                a = s[i+1][j]
            else:
                a = s[i+1][j]+s[i-1][j]
            if j==0:
                b = s[i][j+1]
            elif j==w-1:
                b = s[i][j-1]
            else:
                b = s[i][j-1]+s[i][j+1]
            if not "#" in a+b:
                ans = "No"
                break
    else:
        break
print(ans)