N, M = map(int,input().split()) 
P = [input().split() for i in range(M)]

ans = "Yes"
for n in range(N):
    for m in range(M):
        if p[n][m] == '#':
            if p[n-1][m] == "." and p[n][m-1] == "." and p[n+1][m] == "." and p[n][m+1] == ".":
                ans = "No"
                break
print(ans)