H,W=(int(i) for i in input().split())
s=[input() for i in range(H)]
for i in range(H):
    for j in range(W):
        if s[i][j]=='#':
            if i==0 or s[i-1][j]=='.':
                if i==H-1 or s[i+1][j]=='.':
                    if j==0 or s[i][j-1]=='.':
                        if j==W-1 or s[i][j-1]=='.':
                            print('No')
                            exit()
print('Yes')