H, W = map(int, input().split())
s = ['.'*(W+2)] + ['.'+input()+'.' for i in range(H)] + ['.'*(W+2)]
ans = 'No'
flag = False
for i in range(1, H+1):
    for j in range(1, W+1):
        if s[i][j] == '#':
            ans = 'Yes'
            if not '#' in [s[i-1][j], s[i+1][j], s[i][j-1], s[i][j+1]]:
                ans = 'No'
                flag = True
                break
    if flag:
        break
print(ans)
