h,w=map(int,input().split())
x=[[0]*(w+2)]
for i in range(h):
    x.append([0]+list(input())+[0])
x.append([0]*(w+2))
c=0
for i in range(1,h+1):
    if c==1:
        break
    for j in range(1,w+1):
        if x[i][j]=="#":
            if x[i-1][j]!="#" and x[i][j-1]!="#" and x[i][j+1]!="#" and x[i+1][j]!="#":
                print("NO")
                c+=1
                break
else:
    if c!=1:
        print("Yes")