h, w = map(int, input().split())

sss = [input() for _ in range(h)]

def f(sss, i, j):
    if sss[i][j] == '.':
        return False
    for v in (-1, 1):
        if i+v < 0 or h <= i+v:
            continue
        if sss[i+v][j] == '#':
            return True
    for u in (-1, 1):
        if j+u < 0 or w <= j+u:
            continue
        if sss[i][j+u] == '#':
            return True
    return False

def solve(sss):
    for i in range(h):
        for j in range(w):
            if f(sss, i, j):
                return True
    return False

print("Yes" if solve(sss) else "No")
