h,w=map(int,input().split())
S=[]
for i in range(h):
    s=input()
    S.append(s)
for i in range(1,h-1):
    for j in range(1,w-1):
        if S[i+1][j]==S[i][j+1]==S[i-1][j]==S[i][j-1]==".":
            print("No")
            quit()
print("Yes")