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 '#' not in [s[y][x+1], s[y][x-1], s[y+1][x], s[y-1][x]]:
                ans = 'No'
print(ans)