import sys

H, W = map(int, input().split())

# H = 2
# W = 3

s = [["" for j in range(W)] for i in range(H)]

for i in range(H):
    tmp = input()
    for j in range(W):
        s[i][j] = tmp[j]

# print(s)

for i in range(H):
    for j in range(W):
        if s[i][j] == "#":
            if i != 0:
                if s[i-1][j] == "#":
                    break
            if i != H-1:
                if s[i+1][j] == "#":
                    break
            if j != 0:
                if s[i][j-1] == "#":
                    break
            if j != W-1:
                if s[i][j+1] == "#":
                    break
            print("No")
            sys.exit()
print("Yes")
