import sys
sys.setrecursionlimit(10000)

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

flag = 1
for i in range(h):
    for j in range(w):
        if(i != 0 and s[i][j] == "#" and s[i-1][j] == "#"):
            flag = 1
            break
        else:
            flag = 0

        if(j != w-1 and s[i][j] == "#" and s[i][j+1] == "#"):
            flag = 1
            break
        else:
            flag = 0

        if(i != h-1 and s[i][j] == "#" and s[i+1][j] == "#"):
            flag = 1
            break
        else:
            flag = 0

        if(j != 0 and s[i][j] == "#" and s[i][j-1] == "#"):
            flag = 1
            break
        else:
            flag = 0
    if(flag == 0):
        print("No")
        exit()

print("Yes")