H, W = map(int,input().split())
grid = ['.'*(W+2)]
for _ in range(H):
    tmp = input()
    tmp = '.' + tmp + '.'
    grid.append(tmp)
grid.append('.'*(W+2))
for i in range(1,H+1):
    for k in range(1,W+1):
        if grid[H][W] == '.':
            continue
        if grid[H][W+1] != '#' or grid[H][W-1] != '#':
            if grid[H+1][W] != '#' or grid[H-1][W] != '#':
                print('No')
                exit()
print('Yes')