h, w = map(int, input().split())
s = [list(input()) for _ in range(h)]
for i in range(h):
    for j in range(w):
        if s[i][j] == "#":
            f = False
            if 0 <= i+1 < h and 0 <= i < w and s[i+1][j] == "#":
                f = True
            if 0 <= i-1 < h and 0 <= i < w and s[i-1][j] == "#":
                f = True
            if 0 <= i < h and 0 <= j+1 < w and s[i][j+1] == "#":
                f = True
            if 0 <= i < h and 0 <= j-1 < w and s[i][j-1] == "#":
                f = True
            if not f:
                print("No")
                exit()
print("Yes")
