h,w=map(int,input().split())
a=[]
for i in range(h):
    a.append(list(input()))
judge = True
for i in range(h):
    for j in range(w):
        if a[i][j]==".":
            continue
        if i>0 and a[i-1][j]=="#":
            break
        if j>0 and a[i][j-1]=="#":
            break
        if j<w-1 and a[i][j+1]=="#":
            break
        if i<h-1 and a[i+1][j]=="#":
            break
        judge =False
    if not judge :
        break
print("Yes" if judge else "No")