H, W = map(int, input().split())
s = [list(input()) for i in range(W)]
for i in range(H):
    for j in range(W):
        if s[i][j] == "#":
            count = 4
            if i == 0:
                pass
            else:
                if s[i-1][j] != "#":
                    count -= 1
            if j == 0:
                pass
            else:
                if s[i][j-1] != "#":
                    count -= 1
            if i == H-1:
                pass
            else:
                if s[i+1][j] != "#":
                    count -= 1
            if j == W-1:
                pass
            else:
                if s[i][j+1] != "#":
                    count -= 1
            if count == 0:
                print("No")
                exit()
print("Yes")