from decimal import *
N=int(input())
s = 0
for i in range(N):
    A = input()
    d = Decimal(A)*10**10
    s += int(d)
if s==0:
    print('0.0000000000')
else:
    if s>0:
        s = str(s).zfill(11)
    else:
        s = str(s).zfill(12)
    ans = s[:-10] + '.' + s[-10:]
    print(ans)