main() {
	assert 0 & 0 == 0
	assert 0 & 1 == 0
	assert 1 & 0 == 0
	assert 1 & 1 == 1
	assert 1 & 2 == 0
	assert 1 & 3 == 1
	assert 2 & 0 == 0
	assert 2 & 1 == 0
	assert 2 & 2 == 2
	assert 2 & 3 == 2
	assert 3 & 0 == 0
	assert 3 & 1 == 1
	assert 3 & 2 == 2
	assert 3 & 3 == 3
}