#!/usr/bin/env python3
# †
from fractions import Fraction as frac

def f(a, b):
    sign = '-' if a < 0 else ''
    a = abs(a)
    integer, rem = divmod(a, b)
    v = []
    for _ in range(10):
        rem *= 10
        quo, rem = divmod(rem, b)
        v.append(quo)
    return '{}{}.{}'.format(sign, integer, ''.join(map(str, v)))


###
if __name__ == '__main__':
    n = int(input())
    s = sum(frac(input()) for _ in range(n))
    res = f(s.numerator, s.denominator)
    print(res)