n = int(input())

ret = 0
for _ in range(n):
  a = input()
  p = a.find('.')
  if p == -1:
    a += "0000000000"
  else:
    m = 10 - len(a) + p + 1
    a = a[:p] + a[p+1:]
    a += "".join('0' for _ in range(m))
  ret += int(a)

d = ret // 10000000000
f = ret % 10000000000

print("{}.{:010}".format(d, f))