H, W = map(int, input().split())
G = [list(input()) for _ in range(H)]

ans = 'Yes'
for i in range(H):
    for j in range(W):
        if G[i][j] == '#':
            if i == 0:
                if j == 0:
                    if G[i+1][j] == '#' or G[i][j+1] == '#':
                        continue
                    else:
                        ans = 'No'
                        break
                elif j == W-1:
                    if G[i+1][j] == '#' or G[i][j-1] == '#':
                        continue
                    else:
                        ans = 'No'
                        break
                else:
                    if G[i+1][j] == '#' or G[i-1][j] == '#' or G[i][j-1] == '#' or G[i][j+1] == '#':
                        continue
                    else:
                        ans = 'No'
                        break
    if ans == 'No':
        break

print(ans)