def repaint(h, w, s):
    for i in (1, h+1):
        for p in (1, w+1):
            if s[i][p] == '#':
                if (s[i-1][p] != '#') and (s[i][p+1] != '#') and (s[i+1][p] != '#') and (s[i][p-1] != '#'):
                    return 'No'
    return 'Yes'
H, W = map(int, input().split())
S = [['.']*(W+2)]+[list('.'+input()+'.') for i in range(H)]+[['.']*(W+2)]
print(repaint(H, W, S))