import java.util.Scanner;

public class Riccardo {
    public static void main(String[] args) {
        Scanner kb = new Scanner(System.in);
        int num = kb.nextInt();
        int min = 0;
        int max = kb.nextInt();
        int val = 0;
        boolean primoGiro = true;
        for (int i = 0; i < num; i++, val = kb.nextInt()) {
            if (primoGiro || val > max) {
                max = val;
            }
            if (primoGiro || val < min) {
                min = val;
            }
            primoGiro = false;
        }
        int tot = 0;
        int confronti = 0;
        for (int i = min; i <= max; i++) {
            for (int j = 0; j <= max - min; j++, confronti++) {
                if (i > j) {
                    tot++;
                }
            }
        }
        double rapporto = tot / (double)confronti;

        System.out.println("Tot: " + tot + "; rapporto: " + rapporto);
    }
}