N = int(input())
d_total = 0
f_total = 0
for i in range(N):
    s = input().strip().split(".")
    d = int(s[0])
    if len(s) == 2:
        f = int(s[1])*(10**(10-len(s[1])))
    else:
        f = 0
    if "-" in s[0]:
        f *= -1
    d_total += d
    f_total += f

total = str(d_total * 10**10 + f_total)
d = total[:len(total)-10]
key = 0
for i in d[::-1]:
    if i != "0":
        break
    key -= 1
d_total = int(d[:len(d)-key])
f_total = int(total[len(total)-10:])
print("%d.%010d"%(d_total, f_total))