H, W = map(int, input().split())
s_list = []
for i in range(W):
    s_list.append(input())
cnt = 0
for i in range(1, H):
    for j in range(1, W):
        if s_list[i][j] == '#' and s_list[i][j-1] != '#' and\
           s_list[i-1][j] != '#' and s_list[i][j+1] !='#' and\
                                                       s_list[i+1][j] != '#':
            cnt += 1
if cnt == 0:
    print('Yes')
else:
    print('No')