H,W=map(int, input().split())
field=[[0]*(W+1) for i in range(H+1)]
List=[list(input()) for i in range(H)]

for k in range(1,H):
    for j in range(1,W):
        field[k][j] = List[k-1][j-1]

#print(field)

flag=1

for k in range(1,W):
    for j in range(1,H):
        if field[k][j]=='#' and field[k-1][j]!='#' and field[k+1][j]!='#' and field[k][j-1]!='#' and field[k][j+1]!='#':
            flag=0
            exit()

if flag==1:     
    print('Yes')
else:
    print('No')