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
d_total += f_total // (10**10)
f_total -= (f_total // (10**10)) * (10**10)
print("%d.%010d"%(d_total, f_total))