# -*- coding: utf-8 -*-
h, w = map(int, raw_input().split())

matrix = []
matrix.append('.'*(w+2))

for i in range(w):
    matrix.append('.' + raw_input() + '.')

matrix.append('.'*(w+2))

for i in range(1, h+1):
    for j in range(1, w+1):
        if matrix[i][j] == '#':
            if matrix[i+1][j] == '#' or matrix[i-1][j] == '#' or matrix[i][j-1] == '#' or matrix[i][j+1] == '#':
                continue
            else:
                print 'No'
                exit()
print 'Yes'