h,w=map(int,input().split())
s=[list(input()) for i in range(h)]

dx=[0,1,0,-1]
dy=[1,0,-1,0]
for i in range(h):
    for j in range(w):
        if s[i][j]=='#':
            ans=False
            for k in range(4):
                nx = i+dx[k]
                ny = j+dy[k]
                if nx>=0 and nx <h and ny>=0 and ny<w and s[nx][ny]=='#':
                    ans = True
                    break
            if ans ==False:
                print('No')
                exit()
if ans:
    print('Yes')
            
                