#!/usr/bin/env python3
h,w = map(int,input().split())
grid = [["."]*(w+2) for _ in range(h+2)]
for i in range(h):
    s = input()
    for j in range(w):
        grid[i+1][j+1] = s[j]
for i in range(h):
    for j in range(w):
        if grid[i][j+1] == "."  and  grid[i+1][j] == "." and grid[i-1][j] == "#" and grid[i][j-1] == "#":
            print("No")
            exit()
print("Yes")