def main():
    h, w = map(int, input().split())
    k = [["."]+list(input())+["."] for _ in range(h)]
    s = [[None]*(w+2) for _ in range(h+2)]
    s[0] = ["."]*(w+2)
    s[-1] = ["."]*(w+2)
    s[1:h+1] = k
    d = [[0, 1], [0, -1], [1, 0], [-1, 0]]
    for i in range(1, w+1):
        for j in range(1, h+1):
            if s[i][j] == ".":
                continue
            flag = True
            for (di, dj) in d:
                if s[i+di][j+dj] == "#":
                    flag = False
                    break
            if flag:
                print("No")
                return
    print("Yes")

if __name__ == "__main__":
    main()