ans = 0
n = int(input())
for _ in range(n):
    s = input()
    sub = False
    if s[0] == "-":
        s = s[1:]
        sub = True
    if "." in s:
        a, b = s.split(".")
        b = b[::-1]
    else:
        a, b = s, ""
    a = int(a + "0" * 10)
    b = int(b.zfill(10)[::-1])
    if sub:
        ans -= a + b
    else:
        ans += a + b

d, m = divmod(ans, 10**10)
res = str(d) + "." + str(m)[::-1].zfill(10)[::-1]
print(res)