n = int(input())
ans = 0
for _ in range(n):
	a = input()
	s = 1
	p = 0
	if a[0] == '-':
		s = -1
		a = a[1:]
	if '.' in a:
		d = a.index('.')
		a1 = int(a[:d])
		a2 = a[d + 1:]
		a2 = int(a2) * 10 ** (10 - len(a2))
		p = a1 * 10 ** 10 + a2
	else:
		p = int(a) * 10 ** 10
	ans += s * p
if ans < 0:
	print('-', end = '')
s1 = ans // (10 ** 10)
s2 = ans % (10 ** 10)
print(str(s1) + '.' + str(s2).zfill(10))