#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
#define rep(i, n) REP(i, 0, n)
#define REP(i, s, e) for (ll i = (s); i < (ll)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for (ll i = (ll)(s - 1); i >= (ll)(e); i--)
#define all(r) r.begin(), r.end()
#define rall(r) r.rbegin(), r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

template <typename T, typename U>
bool chmax(T& a, const U& b) {
    if (a >= b) return false;
    a = b;
    return true;
}
template <typename T, typename U>
bool chmin(T& a, const U& b) {
    if (a <= b) return false;
    a = b;
    return true;
}

void yes_no(bool f, string yes = "Yes", string no = "No") {
    cout << (f ? yes : no) << "\n";
}

vector<string> split_string(const string& s, char c = ' ') {
    vector<string> res;
    stringstream ss(s);
    string tmp;
    while (getline(ss, tmp, c)) {
        res.emplace_back(tmp);
    }
    return res;
}

void solve() {
    int n;
    cin >> n;
    vector<string> s(n);
    rep(i, n) cin >> s[i];
    using lint = __int128_t;
    const lint ten = 1e10;
    lint sum = 0;
    rep(i, n) {
        bool pos = true;
        if (s[i][0] == '-') {
            s[i] = s[i].substr(1);
            pos = false;
        }
        auto t = split_string(s[i], '.');
        sum += ten * stol(t[0]) * (pos ? 1 : -1);
        if (t.size() > 1) {
            if (t[1].size() < 10) {
                int m = t[1].size();
                t[1] += string(10 - m, '0');
            }
            sum += stol(t[1]) * (pos ? 1 : -1);
        }
    }
    ll x = sum / ten, y = sum % ten;
    printf("%ld.%0.10ld\n", x, y);
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t = 1;
    // cin >> t;
    rep(ti, t) solve();
    return 0;
}