H,W = sorted(map(int,input().split()))
ss=[]
for s in range(H):
    ss.append(input().strip())
flg=True
for i in range(H):
    for j in range(W):
        if ss[i][j]== "#":
            if not (j>0 and ss[i][j-1] == "#"or j<W-1 and ss[i][j+1] == "#" or i>0 and ss[i-1][j]=="#" or i< H-1 and ss[i+1][j]=="#"):
                flg=False
                break
    if not flg:
        break
print("No Yes".split()[int(flg)])  