use std::collections::{HashMap, HashSet};

use proconio::marker::Chars;

fn main() {
    proconio::input! {
        n: u32,
        mut a: [String;n],
    }
    let a = a
        .into_iter()
        .map(|s| {
            let s = s.split('.').collect::<Vec<_>>();
            if s.len() == 1 {
                [s[0].parse::<i128>().unwrap(), 0]
            } else {
                [
                    s[0].parse::<i128>().unwrap(),
                    s[1].parse::<i128>().unwrap() * (10i128).pow(10 - s[1].len() as u32),
                ]
            }
        })
        .collect::<Vec<_>>();
    for a in a.iter() {
        eprintln!("{a:?}");
    }
    let mut x = 0;
    let mut y = 0;
    for [i, j] in a {
        if i < 0 {
            y = j - y;
            if y < 0 {
                y += 10000000000;
                x -= 1;
            }
            x = i - x;
        } else {
            y += j;
            x += i;
        }
    }
    println!("{}.{:010}", x, y);
}