n = int(input())
a, b = 0, 0
for _ in range(n):
    x, y = input().split('.')
    if x[0] == "-":
        a -= int(x[1:])
        b -= int(y)
    else:
        a += int(x)
        b += int(y)
print(a+b//10**9, b%10**9, sep=".")