#include <bits/stdc++.h>
#define range(i, l, r) for(int (i) = (l); (i) < (r); (i)++)
#define reversed_range(i, l, r) for (int (i) = (r) - 1; (i) >= l; (i)--)
using namespace std;
template <typename T>
using vec = vector<T>;
using lint = long long;
using ulint = unsigned long long;
using pint = pair<int, int>;
using plint = pair<lint, lint>;

template <typename S, typename T>
ostream& operator <<(ostream& os, pair<S, T> p) {
    os << "(";
    os << p.first << ", " << p.second;
    return os << ")";
}

template <typename T>
ostream& operator <<(ostream& os, vec<T> v) {
    os << "[";
    if (v.size() == 0) return os << "]";
    for (int i = 0; i < v.size() - 1; i++) {
        os << v.at(i) << ", ";
    }
    return os << v.at(v.size() - 1) << "]";
}

template <typename T>
ostream& operator <<(ostream& os, set<T>& s) {
    os << "{";
    if (s.begin() == s.end()) return os << "}";
    auto it_first_item = s.begin();
    cout << *it_first_item;
    for (auto it = ++it_first_item; it != s.end(); it++) {
        cout << ", " << *it;
    }
    return cout << "}";
}

template <typename T>
ostream& operator <<(ostream& os, unordered_set<T>& s) {
    os << "{";
    if (s.begin() == s.end()) return os << "}";
    auto it_first_item = s.begin();
    cout << *it_first_item;
    for (auto it = ++it_first_item; it != s.end(); it++) {
        cout << ", " << *it;
    }
    return cout << "}";
}

template <typename K, typename V>
ostream& operator <<(ostream& os, map<K, V> m) {
    os << "{";
    if (m.begin() == m.end()) return os << "}";
    auto it_first_item = m.begin();
    cout << it_first_item->first << ": " << it_first_item->second;
    for (auto it = ++it_first_item; it != m.end(); it++) {
        cout << ", " << it->first << ": " << it->second;
    }
    return os << "}";
}

template <typename K, typename V>
ostream& operator <<(ostream& os, unordered_map<K, V> m) {
    os << "{";
    if (m.begin() == m.end()) return os << "}";
    auto it_first_item = m.begin();
    cout << it_first_item->first << ": " << it_first_item->second;
    for (auto it = ++it_first_item; it != m.end(); it++) {
        cout << ", " << it->first << ": " << it->second;
    }
    return os << "}";
}

lint pow(lint num, lint e, lint MOD) {
    lint res = 1;
    lint cur_num = num;
    while (e) {
        if (e & 1) {
            res *= cur_num;
            res %= MOD;
        }
        cur_num *= cur_num;
        cur_num %= MOD;
        e >>= 1;
    }
    return res;
}

int main() {
    cin.tie(0); cout.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(30);
    lint N;
    cin >> N;
    vec<tuple<lint, lint, double>> engines(N);
    range(i, 0, N) {
        lint x, y;
        cin >> x >> y;
        engines.at(i) = make_tuple(x, y, atan2(x, y));
    }
    sort(engines.begin(), engines.end(),
    [](const tuple<lint, lint, double>& a, const tuple<lint, lint, double>& b) {
        return get<2>(a) < get<2>(b);
    });
    vec<plint> cuml_coord(2 * N);
    lint cur_x = 0, cur_y = 0;
    range(i, 0, 2 * N) {
        cur_x += get<0>(engines.at(i % N));
        cur_y += get<1>(engines.at(i % N));
        cuml_coord.at(i) = {cur_x, cur_y};
    }
    lint squared_res = 0;
    range(j, 0, N)
        squared_res = max(squared_res, cuml_coord.at(j).first * cuml_coord.at(j).first
                        + cuml_coord.at(j).second * cuml_coord.at(j).second);
    range(i, 0, N - 1) range(j, i, N + i) {
        lint x = cuml_coord.at(j).first - cuml_coord.at(i).first;
        lint y = cuml_coord.at(j).second - cuml_coord.at(i).second;
        squared_res = max(squared_res, x * x + y * y);
    }
    cout << sqrt(squared_res) << "\n";
}


Measured memory_bytes: 256