H,W=map(int,input().split())
answers=[]
answers.append([' ',]*(W+2))
for a in range(H):
    S=input()
    T=[b for b in S]
    T.append(' ')
    T.insert(0,' ')
    answers.append(T)
answers.append([' ',]*(W+2))
lll=[]
kotae=0
for a in range(H):
    A=answers[a+1]
    for b in range(W):
        if A[b+1]=='#':
            if A[b]=='#' or A[b+2]=='#'  or answers[a][b+1]=='#' or answers[a+2][b+1]=='#':
                pass
            else:
                kotae+=100
            break
if kotae==0:
    print('Yes')
else:
    print('No')
