h,w=map(int,input().split())
dx=[-1,1,0,0]
dy=[0,0,-1,1]
a=[]
for i in range(h):
    a.append(list(input()))
for i in range(h):
    for j in range(w):
        frag=False
        if a[i][j]=="#":
            for k in range(4):
                x=j+dx[k]
                y=i+dy[k]
                if x<0 or x>w-1 or y<0 or y>h-1:
                    continue
                if a[x][y]=="#":
                    frag=True
            if frag==False:
                print("No")
                exit()
print("Yes")