a, b = map(int, input().split())

A = []
A.append(['.']*(b+2))

for i in range(a):
    
    A.append(list('.'+input()+'.'))
A.append(['.']*(b+2))

ans = 0
for i in range(1, a+2):
    for j in range(1, b+2):
        if(A[i][j] == '#'):
            if(A[i][j-1] != "#" and A[i][j+1] != "#" and A[i-1][j] != "#" and A[i+1][j] != "#"):
                print('No')
                ans += 1
                break
    break
if(ans == 0):
    print('Yes')