#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;

int N;
vector<lint> x, y;
lint ret;

vector<plint> acc(vector<plint> v)
{
    vector<plint> ret{{0, 0}};
    for (auto p : v)
    {
        plint pnew = p + ret.back();
        ret.emplace_back(pnew);
    }
    return ret;
}

void solve()
{
    lint X = 0, Y = 0;

    vector<plint> v1, v2;
    REP(i, N)
    {
        if (x[i] >= 0 and y[i] >= 0)
        {
            X += x[i];
            Y += y[i];
        }
        else if (x[i] > 0)
        {
            v1.emplace_back(x[i], y[i]);
        }
        else if (y[i] > 0)
        {
            v2.emplace_back(x[i], y[i]);
        }
    }
    std::sort(ALL(v1), [](plint l, plint r) { return r.first * l.second > r.second * l.first; });
    std::sort(ALL(v2), [](plint l, plint r) { return r.first * l.second < r.second * l.first; });

    vector<plint> acc1 = acc(v1), acc2 = acc(v2);
    for (auto p1 : acc1) for (auto p2 : acc2)
    {
        plint ptmp = plint(X, Y) + p1 + p2;
        mmax(ret, ptmp.first * ptmp.first + ptmp.second * ptmp.second);
    }
}
int main()
{
    cin >> N;
    x.resize(N);
    y.resize(N);
    REP(i, N) cin >> x[i] >> y[i];
    ret = 0;

    REP(d, 4)
    {
        solve();
        REP(i, N) x[i] = -x[i];
        if (d % 2)
        {
            REP(i, N) y[i] = -y[i];
        }
    }
    cout << sqrt((double)ret) << endl;
}


Measured memory_bytes: 256