/*import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] a = new int[n];
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
        }
    }
}*/
import java.io.*;
public class array
    {
    public static void main()throws IOException
        {
        int n;int i,j;int k=0;int p,q,t;int c=0;
        InputStreamReader read=new InputStreamReader(System.in);
        BufferedReader in=new BufferedReader(read);
        n=Integer.parseInt(in.readLine());
        if(n>=2 && n<=100)
            {
            int arr[]=new int[n];
            for(i=0;i<n;i++)
                {
                arr[i]=Integer.parseInt(in.readLine());
               
            }
            for(i=0;i<n;i++)
                {
                if(arr[i]>0 && arr[i]<100)
                    c++;
            }
            if(c==n)
                {
            for(i=0;i<n-1;i++)
                {
                for(j=i+1;j<n;j++)
                    {
                    p=arr[i];
                    q=arr[j];
                    if(p>q)
                        t=p-q;
                    else
                        t=q-p;
                    if(t>=1)
                        k++;
                }
            }
                
            System.out.println(k);
            }
            

        }
    }
}