def main():
	N = input('N: ')
	i = 1
	Sx2 = 0.0
	Sx = 0.0
	Sy = 0.0
	Sxy = 0.0
	while (i <= N):
		print "digite X", i,
		x = float(input(':'))
		print "digite Y", i,
		y = float(input(':'))
		Sx2 = Sx2 + x**2
		Sx = Sx + x
		Sy = Sy + y
		Sxy = Sxy + x * y
		i += 1
	print "Sx2 : ", Sx2, "\nSx : ", Sx, "\nSy : ", Sy, "\nSxy : ", Sxy, "\nDelta : ", (N * Sx2 - Sx**2)


if __name__ == '__main__':
    main()