H, W = list(map(int, input().split()))
s = ['.'*(W+2)] + ['.'+input()+'.' for i in range(H)] + ['.'*(W+2)]

ans = 'Yes'
for y in range(1, W+1):
    for x in range(1, H+1):
        if s[y][x] == '#':
            if '.' == s[y][x+1] and '.' == s[y][x-1] and '.' == s[y+1][x] and '.' == s[y-1][x]:
                ans = 'No'
print(ans)