def solve(H, W, S):
    for h in range(1, H):
        for w in range(1, W):
            if S[h][w] == '#':
                if not (S[h-1][w] == '#' or S[h+1][w] == '#' or S[h][w+1] == '#' or S[h][w-1] == '#'):
                    return "No"
    return "Yes"


H, W = [int(x) for x in input().split()]
# H, W < 50
S = []
S.append('.' * (H+2))
for _ in range(H):
    S.append("."+input().strip()+".")
S.append('.' * (H+2))
print(solve(H, W, S))

