N, M = map(int, input().split())
a = []
tmp = []
for i in range(M):
    tmp = list(map(str,input().split()))
    a.append(list(tmp[0]))


cpi = [-1,0,0,1]
cpj = [0,-1,1,0]

smFlag = False
result = True

for i in range(N):
    for j in range(M):
        if a[i][j] == '#':
            for x,y in zip(cpi,cpj):
                if i + x > -1 and j + y > -1 and i + x < N  and j + y < M:
                    if a[i+x][j+y] == '#':
                        smFlag = True
            if not smFlag:
                print('No')
                result = False

if result:
    print('Yes')
