def resolve():
    h, w = map(int, input().split())
    l = []
    for i in range(h):
        s = list(input())
        l.append(s)

    d = [[-1, 0], [0, -1], [0, 1], [1, 0]]

    count = 0
    for i in range(h):
        for j in range(w):

            for dx, dy in d:
                m = i + dx
                n = j + dy
                if m < 0 or m > h - 1:
                    pass
                elif n < 0 or n > w - 1:
                    pass
                elif l[i][j] == '#' and l[m][n] == '#':
                    count += 1

    if count == 0:
        return print('No')
    else:
        return print('Yes')

if __name__ == '__main__':
    resolve()
