import sys
H,W = input().split()
H = int(H)
W = int(W)
s = []

s.append("."*(W+1))
for i in range(H):
    s.append("."+input()+".")

s.append("."*(W+2))

for j in range(1,1+H):
    for i in range(1,1+W):
#        print(i,j,s[i][j])
        if s[i][j] == "#":
            if s[i][j-1] != "#" and s[i][j+1] != "#" and s[i-1][j] != "#" and s[i+1][j] != "#":
                print("No")
#                print(s[i][j-1],s[i][j+1], s[i-1][j],s[i+1][j])
                sys.exit()



print("Yes")
