module main;

import std;

void main()
{
	// 入力
	int N = readln.chomp.to!int;
	// 答えの計算と出力
	BigInt ans = 0;
	immutable divisor = BigInt(10L ^^ 10);
	foreach (_; 0 .. N) {
		auto A = readln.chomp.split(`.`);
		BigInt sign = 1;
		if (A[0][0] == '-') {
			sign = -1;
			A[0] = A[0][1 .. $];
		}
		ans += sign * BigInt(A[0]) * divisor;
		if (A.length == 2)
			ans += sign * BigInt(A[1] ~ "0".replicate(max(10 - A[1].length, 0)));
	}
	writefln(`%d.%010d`, ans / divisor, ans % divisor);
}