import sys
H, W = map(int, input().split())
s = [input() for i in range(H)]
S = []
S.append('.' * (W + 2))
for i in range(W):
    S.append('.' + s[i] + '.')
S.append('.' * (W + 2))
for i in range(1, H + 1):
    for j in range(1, W + 1):
        if S[i][j] == '#':
            if S[i + 1][j] == '#' or S[i - 1][j] == '#' or S[i][j + 1] == '#' or S[i][j - 1] == '#':
                continue
            else:
                print('No')
                sys.exit()
print('Yes')