public class Flee {

    boolean check(int[] x, int[] y, double r)
    {
        int n = x.length;
        for(int i = 0; i < n; i++)
            if(x[i]*x[i] + y[i]*y[i] <= r*r)
                return true;
        boolean linked[][] = new boolean[n][n];
        for(int i = 0; i < n; i++)
            for(int j = 0; j < n; j++)
                if((x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]) <= 4*r*r)
                    linked[i][j] = true;
        for(int start = 0; start < n; start++)
        {
            double[] maxVal = new double[n];
            for(int i = 0; i < n; i++)
                maxVal[i] = -1000;
            maxVal[start] = 0;
            for(int iteration = 1; iteration <= n; iteration ++)
            {
                for(int i = 0; i < n; i++)
                    for(int j = 0; j < n; j++)
                        if(linked[i][j])
                        {
                            double delta = Math.atan2(y[j], x[j]) - Math.atan2(y[i], x[i]);
                            if(Math.abs(delta + Math.PI * 2) < Math.abs(delta))
                                delta = delta + Math.PI * 2;
                            else if(Math.abs(delta - Math.PI*2) < Math.abs(delta))
                                delta = delta - Math.PI * 2;
                            maxVal[j] = Math.max(maxVal[j], maxVal[i] + delta);
                        }
            }
            if(maxVal[start] >= 2 * Math.PI - 1e-9)
                return true;
        }
        return false;
    }

    public double maximalSafetyLevel(int[] x, int[] y)
    {
        double L = 0, R = 2000, M = 0;
        for(int iteration = 1; iteration <= 100; iteration ++)
        {
            M = (L + R) / 2;
            if(check(x, y, M))
                R = M;
            else
                L = M;
        }
        return M;
    }
}