def g2():
    hw=[int(i) for i in input().split()]
    s=['.'+input()+'.' for i in range(hw[0])]
    s=['.'*(hw[1]+2)]+s+['.'*(hw[1]+2)]
    for i in range(1,hw[1]+1):
        for n in range(1,hw[0]+1):
            if s[i][n]=='#':
                if s[i+1][n]=='.' and s[i][n+1]=='.' and s[i-1][n]=='.' and s[i][n-1]=='.':
                    print('No')
                    exit()
    print('Yes')
    exit()
print(g2())