n = int(input())
total = 0
for _ in range(n):
    A = input()
    if "." in A:
        keta = len(A[A.find(".") + 1:])
        A = A.replace(".", "")
        total += int(A) * 10 ** (10 - keta)
    else:
        total += int(A) * (10 ** 10)
if total >= 0:
    print(str(total//10**10), str(total%10**10).ljust(10, '0'), sep=".")
else:
    print(str(~total//10**10), str(10**10 - total%10**10).ljust(10, '0'), sep=".")