#include <bits/stdc++.h>
using namespace std;
#define Rep(i,n) for(int i=0;i<(int)(n);i++)
#define For(i,n1,n2) for(int i=(int)(n1);i<(int)(n2);i++)
#define REP(i,n) for(ll i=0;i<(ll)(n);i++)
#define RREP(i,n) for(ll i=((ll)(n)-1);i>=0;i--)
#define FOR(i,n1,n2) for(ll i=(ll)(n1);i<(ll)(n2);i++)
#define RFOR(i,n1,n2) for(ll i=((ll)(n1)-1);i>=(ll)(n2);i--)
#define all(a)  (a).begin(),(a).end()
#define SORT(a) sort((a).begin(),(a).end())
#define oorret 0
#define oor(x) [&](){try{x;} catch(const out_of_range& oor){return oorret;} return x;}()
#define IOS cin.tie(0),ios::sync_with_stdio(false)
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
template<typename T1, typename T2> inline bool chmin(T1& a, T2 b) { if (a > b) { a = b; return 1; }return 0; }
template<typename T1, typename T2> inline bool chmax(T1& a, T2 b) { if (a < b) { a = b; return 1; }return 0; }
template<class Type>struct is_vector : std::false_type {};
template<class ValueType, class Alloc>struct is_vector<std::vector<ValueType, Alloc>> : std::true_type {};
template <typename T> inline ostream& operator << (ostream& out, const vector<T>& v) {
	if (v.empty())return out;
	constexpr bool is_vector_v = is_vector<T>::value;
	if (is_vector_v)for (auto itr = v.begin(); itr != v.end();)out << (*itr), out << ((++itr != v.end()) ? "\n" : "");
	else for (auto itr = v.begin(); itr != v.end();)out << (*itr), out << ((++itr != v.end()) ? " " : "");
	return out;
}
inline void put() {}
template<class T> inline void put(const T& first) { std::cout << first << "\n"; }
template<class T, class... N> inline void put(const T& first, const N& ... rest) { std::cout << first << " "; put(rest...); }
inline void putn() {}
template<class T, class... N> inline void putn(const T& first, const N& ... rest) { std::cout << first << "\n"; putn(rest...); }

template<typename T>//long long or long double
struct vec {
	T x, y;
	vec(T x, T y) :x(x), y(y) {}
	vec() :x(0), y(0) {}
	T prod(vec v) const {
		return x * v.x + y * v.y;
	}
	long double abs() const {
		return sqrtl( x * x + y * y);
	}
	vec operator+(const vec v) const {
		return vec(x + v.x, y + v.y);
	}
	T operator*(const vec v) const {
		return prod(v);
	}
	vec& operator+=(const vec v) {
		(*this) = (*this) + v;
		return *this;
	}
	vec& operator*=(const T v) {
		x *= v;
		y *= v;
		return (*this);
	}
	double rad() const {
		return atan2<double>(y, x);
	}
	bool operator<(const vec& v) const {
		return rad() < v.rad();
	}
};

int main() {
	IOS;
	int n;
	cin >> n;
	using ld = long double;
	vector<ll> x(n), y(n);
	vector<vec<ld>> p(n);
	REP(i, n) {
		cin >> x[i] >> y[i];
		p[i] = vec<ld>(x[i], y[i]);
	}
	sort(all(p));
	ld res = 0;
	const double pi = acos(-1.0);
	REP(i, n) {
		vec<ld> tmp = p[i];
		REP(j, n) {
			if (i != j) {
				ll t1 = p[i] * p[j];
				if (t1 >= 0) {
					tmp += p[j];
				}
			}
		}
		chmax(res, tmp.abs());
	}
	ll cons = 1e6;
	REP(i, cons) {
		vec<ld> tmp;
		vec<ld> t2(cosl((ld)pi * 2 * i / cons), sinl((ld)pi * 2 * i / cons));
		t2 *= cons;
		REP(i, n) {
			ll t1 = p[i] * t2;
			if (t1 >= 0) {
				tmp += p[i];
			}
		}
		chmax(res, tmp.abs());
	}
	cout << setprecision(30) << res << endl;
	return 0;
}


Measured memory_bytes: 512