H,W=map(int,input().split())
S=[input() for i in range(H)]


for h in range(H):
    for w in range(W):
        lst=[]
        if h>1:
            lst.append([-1,0])
        if w>1:
            lst.append([0,-1])
        if h<H-1:
            lst.append([1,0])
        if w<W-1:
            lst.append([0,1])

        if S[h][w]=="#":
            flag=0
            for y,x in lst:
                if S[h+y][w+x]=="#":
                    flag=1
                    break
            if not flag:
                print("No")
                exit()
print("Yes")
