h,w = map(int,input())
L = [input() for i in range(h)]
ans = "ahe"
if L[0][0]=="#" and (L[0][1]=="." and L[1][0]=="."):
    ans="No"
elif L[0][w]=="#" and (L[0][w-1]=="." and L[1][w]=="."):
    ans="No"
elif L[h][0]=="#" and (L[h][1]=="." and L[h-1][0]=="."):
    ans="No"
elif L[h][w]=="#" and (L[h][w-1]=="." and L[h-1][w]=="."):
    ans="No"
for i in range(1,w):
    if L[0][i]=="#" and (L[0][i+1]=="." and L[1][i] =="." and L[1][i-1]):
        ans="No"
for i in range(1,w):
    if L[h][i]=="#" and (L[h][i+1]=="." and L[h-1][i] =="." and L[h][i-1]):
        ans="No"
for i in range(1,h):
    if L[i][0]=="#" and (L[i][1]=="." and L[i+1][0]=="." and L[i-1][0]=="."):
        ans="No"
for i in range(1,h):
    if L[i][w]=="#" and (L[i][w-1]=="." and L[i+1][w]=="." and L[i-1][w]==".")
for i in range(1,h):
    for j in range(1,w):
        if L[i][j]=="#" and (L[i+1][j]=="." and L[i-1][j]=="." and L[i][j+1]=="." and L[i][j-1]=="."):
            ans="No"
if ans !="No":
    ans ="Yes"
print(ans)