import sys

sys.setrecursionlimit(200000000)

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


str_list.append(["."]*w)
str_list.insert(0,["."]*w)
for i in range(h+2):
    str_list[i].append(".")
    str_list[i].insert(0,".")




for i in range(h):
    for j in range(w):
        if str_list[i+1][j+1] == ".":
            continue
        
        for a,b in enumerate([1,2]):
            write = 0

            if str_list[i+a][j+b]=="#":
                write = 1
                break
            
            if str_list[i+b][j+a]=="#":
                write = 1
                break
                

        
        if write == 0:
            break
    else:
        continue
    break
        

            

if write == 1:
    print("Yes")
else:
    print("No")