h, w = map(int, input().split())
s = [list(input()) for _ in range(h)]

ans = "Yes"
for i in range(h):
    for j in range(w):
        if s[i][j] == '#':
            ok = False
            if 1 < i and s[i - 1][j] == '#':
                ok = True
            if i + 1 < h and s[i + 1][j] == '#':
                ok = True
            if 1 < j and s[i][j - 1] == '#':
                ok = True
            if j + 1 < w and s[i][j + 1] == '#':
                ok = True
            if not ok:
                ans = "No"
print(ans)