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

for w in range(1, W+1):
    for h in range(1, H+1):
        if s[w][h] == '#':
            if '#' not in [s[w-1][h], s[w+1][h], s[w][h-1], s[w][h+1]]:
                ans = 'No'
print(ans)