import java.util.Scanner;

public class Accident {
    private static double intX;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double[][] vector = new double[3][2];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 2; j++) {
                vector[i][j] = sc.nextInt();
            }
        }
        double minimum = Double.MAX_VALUE;
        for (int i = 0; i < 3; i++) {
            double preponaX = vector[i][0] + vector[(i + 1) % 3][0];
            double preponaY = vector[i][1] + vector[(i + 1) % 3][1];
            double dlzkaPreponaX = Math.sqrt(preponaX * preponaX + preponaY * preponaY);
            double cs = Math.sqrt(Math.pow((vector[i][0] + vector[(i + 1) % 3][0]) / 2 - (vector[(i + 2) % 3][0]), 2) + Math.pow((vector[i][1] + vector[(i + 1) % 3][1]) / 2 - (vector[(i + 2) % 3][1]), 2));
            double as = Math.sqrt(Math.pow((vector[i][0] - vector[(i + 1) % 3][0]) / 2, 2) + Math.pow((vector[i][1] - vector[(i + 1) % 3][1]) / 2, 2));

            minimum = Math.min(minimum, Math.abs(cs - as));
        }
        System.out.println(minimum);
    }
}