#include <bits/stdc++.h>
#define mem(ar,num) memset(ar,num,sizeof(ar))
#define me(ar) memset(ar,0,sizeof(ar))
#define lowbit(x) (x&(-x))
#define forn(i,n) for(int i = 0;i < n; ++i)
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
const int    prime = 999983;
const int    INF = 0x7FFFFFFF;
const LL     INFF = 0x7FFFFFFFFFFFFFFF;
const double pi = acos(-1.0);
const double inf = 1e18;
const double eps = 1e-10;
const LL     mod = 1e9 + 7;
struct Point
{
	double x, y;

	Point(double x = 0, double y = 0): x(x), y(y) {}

};
typedef Point Vector;
Vector operator + (Vector A, Vector B)
{
	return Vector(A.x + B.x, A.y + B.y);
}
Vector operator - (Vector A, Vector B)
{
	return Vector(A.x - B.x, A.y - B.y);
}
Vector operator / (Vector A, double p)
{
	return Vector(A.x / p, A.y / p);
}
Vector operator * (Vector A, double p)
{
	return Vector(A.x * p, A.y * p);
}
double angle(Vector v)//求向量的角度从0到2*pi
{
	return atan2(v.y, v.x);
}
int dcmp(double x)
{
	if (fabs(x) < eps)
		return 0;
	else
		return x < 0 ? -1 : 1;
}
bool operator < (const Point &a, const Point &b)
{
	if (dcmp(a.x - b.x) == 0)
		return a.y < b.y;
	else
		return a.x < b.x;
}


bool operator == (const Point &a, const Point &b)
{
	return !dcmp(a.x - b.x) && !dcmp(a.y - b.y);
}
double Dot(Vector A, Vector B)
{
	return A.x * B.x + A.y * B.y;
}
double Length(Vector A)
{
	return sqrt(A.x * A.x + A.y * A.y);
}
double Angle(Vector A, Vector B)
{
	return acos(Dot(A, B) / Length(A) / Length(B));
}
double Cross(Vector A, Vector B)
{
	return A.x * B.y - A.y * B.x;
}
double Area2(Point A, Point B, Point C)
{
	return Cross(B - A, C - A);
}
Vector Rotate(Vector A, double rad)
{
	return Vector (A.x * cos(rad) - A.y * sin(rad), A.x * sin(rad) + A.y * cos(rad));
}
Vector Normal(Vector A)//单位法线
{
	double L = Length(A);
	return Vector(-A.y / L, A.x / L);
}
//调用前确保直线有唯一交点，当且仅当Cross(v,w)非0
Point Get_Line_Intersection(Point P, Vector v, Point Q, Vector w)
{
	Vector u = P - Q;
	double t = Cross(w, u) / Cross(v, w);
	return P + v * t;
}
double Distance_To_Line(Point P, Point A, Point B) //点到直线的距离
{
	Vector v1 = B - A, v2 = P - A;
	return fabs(Cross(v1, v2) / Length(v1));
}
double Distance_To_Segment(Point P, Point A, Point B)
{
	if (A == B)
		return Length(P - A);
	Vector v1 = B - A, v2 = P - A, v3 = P - B;
	if (dcmp(Dot(v1, v2)) < 0)
		return Length(v1);
	else if (dcmp(Dot(v1, v3)) > 0)
		return Length(v3);
	else
		return fabs(Cross(v1, v2)) / Length(v1);
}
Point Get_Line_Projection(Point P, Point A, Point B) //求投影点
{
	Vector v = B - A;
	return A + v * (Dot(v, P - A) / Dot(v, v));
}
//线段相交判定 相交不在线段的端点
bool Segment_Proper_Intersection(Point a1, Point a2, Point b1, Point b2)
{
	double c1 =  Cross(a2 - a1, b1 - a1), c2 = Cross(a2 - a1, b2 - a1),
	       c3 =  Cross(b2 - b1, a2 - b1), c4 = Cross(b2 - b1, a1 - b1);
	return dcmp(c1) * dcmp(c2) < 0 && dcmp(c3) * dcmp(c4) < 0;
}
//判断点是否在线段上(不包括端点）
bool Onsegment(Point p, Point a1, Point a2)
{
	return dcmp(Cross(a1 - p, a2 - p)) == 0 && dcmp(Dot(a1 - p, a2 - p)) < 0;
}

bool cmp1(Point a, Point b)
{
	if (atan2(a.y, a.x) != atan2(b.y, b.x))
		return atan2(a.y, a.x) < atan2(b.y, b.x);
	else return a.x < b.x;
}
const int maxn = 200 + 10;
Point p[maxn];

int main(void) {
	int n; cin >> n;
	for (int i = 1; i <= n; ++i)
		cin >> p[i].x >> p[i].y;
	sort(p + 1, p + n + 1, cmp1);
	for (int i = n + 1; i <= 2 * n; ++i)
		p[i] = p[i - n];
	double ans = 0;
	for (int i = 1; i <= n; ++i) {
		Vector v;
		v = v + p[i];
		ans = max(ans, Length(v));
		for (int j = 1; j < n; ++j) {
			v = v + p[j + i];
			ans = max(ans, Length(v));
		}
	}
	printf("%.20f\n", ans);
}



Measured memory_bytes: 256