H, W = map(int, input().split())
Ss = [[j for j in input()] for i in range(H)]

mapping = {'.':0, '#':1}

ans = 'Yes'
for i in range(H):
    for j in range(W):
        if Ss[i][j] == '#':
            counter = 0
            
            if j>0:
                counter += mapping[Ss[i][j-1]]
            if i>0:
                counter += mapping[Ss[i-1][j]]
            if i<H-1:
                counter += mapping[Ss[i+1][j]]
            if j<W-1:
                counter += mapping[Ss[i][j+1]]
      
            if counter == 0:
                ans = 'No'
                break
        else:
        	continue
    break

print(ans)