import sys
h,w=map(int,input().split())
maze=[]
for i in range(w):
    maze.append(list(input()))
for i in range(w):
    for j in range(h):
        if maze[i][j]=="#":
            flg=False
            for l,m in [(0,1),(1,0),(-1,0),(0,-1)]:
                if 0<=i+l<w and 0<=j+m<h:
                    if maze[i+l][j+m]=="#":
                        flg=True
            if flg==False:
                print("No")
                sys.exit()
print("Yes")