height,width=map(int,input().split())
graph = [[s for s in input()] for i in range(height)]

for r in range(width):
    for c in range(height):
        if graph[r][c]==".":
            continue

        if r>0 and graph[r-1][c]=="#":
            continue

        if r<width-1 and graph[r+1][c]=="#":
            continue

        if c>0 and graph[r][c-1]=="#":
            continue

        if c<height-1 and graph[r][c+1]=="#":
            continue

        print("No")
        exit()
print("Yes")