def enumerate_square(i, n):
	"""
	Given i in the range(n^2-n) compute a bijective mapping
	range(n^2-n) -> range(n)*range(n-1) 
	"""
	row = int(i // (n-1))
	col = int(i % (n-1))
	if col >= row:
		col += 1
	return row, col