h, w = map(int, input().split())
s = [['.']*(w+2)] + [['.']+list(input())+['.'] for _ in range(w)] + [['.']*(w+2)]
for i in range(1, w+1):
    for j in range(1, w+1):
        if s[i][j] == '.': continue
        if s[i-1][j] == '.' and s[i][j-1] == '.' and s[i][j+1] == '.' and s[i+1][j] == '.':
            print('No')
            exit()
print('Yes')