H, W = map(int, input().split())
S = [list(map(str,input())) for i in range(H)]

if S[0][0] == '#' and S[0][1] == S[1][0] == '.':
    print('No')
elif S[0][H-1] == '#' and S[0][H-2] == S[1][H-1] == '.':
    print('No')
elif S[W-1][0] == '#' and S[W-2][0] == S[W-1][1] == '.':
    print('No')
elif S[W-1][H-1] == '#' and S[W-2][H] == S[W][H-2] == '.':
    print('No')
else:
    print('Yes')