h,w=map(int,input().split())
a=[0]*(w+2)
m=[a]
ans='Yes'
for i in range(h):
    s=input()
    m.append([0]+[1 if x=='#' else 0 for x in s]+[0])
m.append(a)
for i in range(1,h+1):
    for j in range(1,w+1):
        if sum(m[i][j-1:j+2],m[i-1][j]+m[i+1][j])==1:
            ans='No'
print(ans)
