N = int(input())
ans = 0
for i in range(N):
    n = input()
    pm = 1
    if n[0] == "-":
        n = n[1:]
        pm = -1
    if "." in n:
        X, Y = n.split(".")
        ans += int(X) * 10 ** 10 * pm
        ans += int(Y + "0" * (10 - len(Y))) * pm
    else:
        ans += int(n) * 10 ** 10 * pm
    X = ans // (10 ** 10)
    Y = str(ans % (10 ** 10))
    Y += "0" * (10 - len(Y))
print(str(X) + "." + str(Y))