import sys


def input(): return sys.stdin.readline().strip()


def solve():
    pass


def main():
    H, W = map(int, input().split())
    s = [['.' for _ in range(W+2)] for _ in range(H+2)]
    for i in range(H):
        tmp = list(input())
        for j in range(W):
            s[i+1][j+1] = tmp[j]

    #       Up Left Down Right
    d = zip([0, -1, 0, 1],
            [-1, 0, 1, 0])
    for i in range(1, H+1):
        for j in range(1, W+1):
            if s[i][j] == '.':
                continue

            count = 0
            for dx, dy in d:
                if s[i+dy][j+dx] == '.':
                    count += 1

            if count == 4:
                print('No')
                return

    print('Yes')


if __name__ == "__main__":
    main()
