#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

pair<long long, long long> add(long long a1, long long b1, long long a2, long long b2)
{
    a1 += a2;
    b1 += b2;
    if(b1 >= 10000000000LL){
        ++ a1;
        b1 -= 10000000000LL;
    }
    return make_pair(a1, b1);
}

pair<long long, long long> sub(long long a1, long long b1, long long a2, long long b2)
{
    a1 -= a2;
    b1 -= b2;
    if(b1 < 0){
        -- a1;
        b1 += 10000000000LL;
    }
    return make_pair(a1, b1);
}

int main()
{
    int n;
    cin >> n;

    bool sign = true;
    long long a = 0;
    long long b = 0;
    for(int i=0; i<n; ++i){
        string s;
        cin >> s;
        int k = s.find('.');

        bool sign2 = s[0] != '-';
        long long a2, b2;
        if(k == string::npos){
            if(sign2)
                a2 = stoll(s);
            else
                a2 = stoll(s.substr(1));
            b2 = 0;
        }
        else{
            string x = s.substr(0, k);
            string y = s.substr(k+1);
            y.resize(10, '0');
            if(sign2)
                a2 = stoll(x);
            else
                a2 = stoll(x.substr(1));
            b2 = stoll(y);
        }

        if(sign == sign2){
            tie(a, b) = add(a, b, a2, b2);
        }
        else if(make_pair(a, b) < make_pair(a2, b2)){
            sign = sign2;
            tie(a, b) = sub(a2, b2, a, b);
        }
        else{
            tie(a, b) = sub(a, b, a2, b2);
        }
    }

    if(!sign)
        cout << '-';
    cout << a << '.' << setfill('0') << setw(10) << b << endl;

    return 0;
}