from itertools import product
import numpy as np
h, w = map(int, input().split())
c = np.array(
    [[0 if i == "." else 1 for i in input()] for j in range(h)])

dxt = (1, 0, -1, 0)
dyt = (0, 1, 0, -1)

for i, j in product(range(h), range(w)):
    if c[i, j] == 1:
        ok = False
        for dx, dy in zip(dxt, dyt):
            p, q = i+dx, j+dy
            p, q = max(p, 0), max(q, 0)
            p, q = min(p, h-1), min(q, w-1)
            if c[p, q] == 1:
                ok = True
                break
        if ok is False:
            break
print('Yes') if ok else print('No')