# coding: utf-8
# Your code here!
H,W=map(int,input().split())
l=[]

def dfs(h,w):
    judge=True
    if h!=H:
        dfs(h+1,w)
        judge=False
    if w!=W:
        dfs(h,w+1)
        judge=False
    if h!=0:
        dfs(h-1,w)
        judge=False
    if w!=0:
        dfs(h,w-1)
        judge=False
    if judge:
        print("No")
        exit()

for _ in range(H):
    l.append(list(input()))

for h in H:
    for w in W:
        if w="#"
            dfs(h,w)

print("Yes")
#ほぞん