#include <bits/stdc++.h>

using namespace std;

const long double pi = acos(- 1);

bool equals(long double a, long double b)
{
	return abs(a - b) <= 1e-12;
}

struct point
{
	long double x, y;
	point() {}
	point(const long double &a, const long double &b)
	{
		x = a, y = b;
	}
	long double dist(const point &a)
	{
		return hypot(x - a.x, y - a.y);
	}
	point rotating(const point &a, const long double &b)
	{
		long double xx = (x - a.x) * cos(b) - (y - a.y) * sin(b);
		long double yy = (x - a.x) * sin(b) + (y - a.y) * cos(b);
		return point(xx + a.x, yy + a.y);
	}
};

int main()
{
	ios_base :: sync_with_stdio(false); cin.tie(0); cout.tie(0);
	#ifndef  ONLINE_JUDGE
	freopen("test.inp", "r", stdin);
	freopen("test.out", "w", stdout);
	#endif
	int n;
	cin >> n;
	vector <point> p(n);
	for (int i = 0; i < n; ++i)
		cin >> p[i].x >> p[i].y;
	long double l = 2.0, r = 1e18;
	int cnt = 0;
	while (equals(l , r) == false && (++cnt) <= 499)
	{
		long double m = (l + r) / 2.0;
		bool checking = true;
		long double left = 0.0, right = pi / 2.0, down = pi / 2.0, up = 0.0;
		for (int i = 0; i < n; ++i)
		{
			long double d = p[i].dist(point(0.0, 0.0));
			if (equals(d, m / 2.0) == false && d < m / 2.0)
			{
				checking = false;
				break;
			}
			if (equals(d, m / sqrt(2.0)) == true || d > m / sqrt(2.0))
				continue;
			long double angle = atan2(p[i].y, p[i].x);
			if (angle < 0)
				angle += pi;
			if (angle >= pi / 2.0 && angle <= pi)
				angle -= pi / 2.0;
			long double arccos = acos(m / (2.0 * d));
			long double arcsin = asin(m / (2.0 * d));
			long double l = m / 2.0;
			if (- l < p[i].x && p[i].x < l && - l < p[i].y && p[i].y < l)
			{
				left = max(left, angle - arccos);
				right = min(right, angle + arccos);
				if (left > right)
				{
					checking = false;
					break;
				}
			}
			else
			{
				if (angle <= pi * 0.75)
				{
					down = min(down, angle + arccos);
					up = max(up, angle - arccos + pi / 2.0);
				}
				else
				{
					down = min(down, angle - arcsin);
					up = max(up, angle - arccos);
				}
			}
			if (left > down && right < up)
			{
				checking = false;
				break;
			}
		}
		if (checking == true)
			l = m;
		else
			r = m;
	}
	cout << fixed << setprecision(4) << l * 4.0;
}