h,w = map(int,input().split())
s = [list(input()) for _ in range(h)]
visited = [[False]*w for _ in range(h)]
for y in range(h):
    for x in range(w):
        if s[y][x]=="#" and not visited[y][x]:
            visited[y][x]= True
            flag =False
            for dy,dx in ((1,0),(-1,0),(0,1),(0,-1)):
                ny,nx = y+dy,x+dx
                if 0<=ny<h and 0<=nx<w and s[ny][nx]=='#':
                    visited[ny][nx] = True
                    flag = True
                    
            if flag ==False:
                print('No')
                break
    if not flag:
        break
    

if flag:
    print('Yes')