H, W = list(map(int, input().split()))
s = []
s.append(['.']*(W+2))
for i in range(W):
    #二次元配列に入力を入れる
    array =['.']
    array.extend(list(input()))
    array.extend(['.'])
    s.append(array)
s.append(['.']*(W+2))
count = 0
for i in range(1,W+1):
    for j in range(1,H+1):
        if(s[i][j] == '#' and s[i][j-1] != '#' and s[i][j+1] != '#' and s[i-1][j] != '#' and s[i+1][j] != '#'):
            count += 1

if (count==0):
    print("Yes")
else:
    print("No")
