Let's denote a function 

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You are given an array a consisting of n integers. You have to calculate the sum of d(ai, aj) over all pairs (i, j) such that 1 ≤ i ≤ j ≤ n.

Input

The first line contains one integer n (1 ≤ n ≤ 200000) — the number of elements in a.

The second line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 109) — elements of the array. 

Output

Print one integer — the sum of d(ai, aj) over all pairs (i, j) such that 1 ≤ i ≤ j ≤ n.

Examples

Input

5
1 2 3 1 3


Output

4


Input

4
6 6 5 5


Output

0


Input

4
6 6 4 4


Output

-8

Note

In the first example:

  1. d(a1, a2) = 0; 
  2. d(a1, a3) = 2; 
  3. d(a1, a4) = 0; 
  4. d(a1, a5) = 2; 
  5. d(a2, a3) = 0; 
  6. d(a2, a4) = 0; 
  7. d(a2, a5) = 0; 
  8. d(a3, a4) = - 2; 
  9. d(a3, a5) = 0; 
  10. d(a4, a5) = 2. 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.TreeMap;
import java.util.TreeSet;
public class Main {
    public static long[] t1 = new long[200005];
    public static long[] t2 = new long[200005];
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        int[] a = new int[n];
        String[] in = br.readLine().split(" ");
        TreeSet<Integer> all = new TreeSet<>();
        all.add(0); all.add(1000000001);
        for (int i = 0;i < n;i++) {a[i] = Integer.parseInt(in[i]); all.add(a[i]);}
        ArrayList<Integer> srt = new ArrayList<>();
        for (int x : all) srt.add(x);
        TreeMap<Integer,Integer> m = new TreeMap<>();
        for (int i = 0;i < srt.size();i++) m.put(srt.get(i),i+1);
        BigInteger ans = new BigInteger("0");
        for (int i = 0;i < n;i++) {
            int tmp = m.get(a[i])-1; if (srt.get(tmp-1) == srt.get(tmp)-1) tmp--;
            Long s1 = query1(tmp)*a[i]-query2(tmp);
            ans = ans.add(new BigInteger(s1.toString()));
            tmp = m.get(a[i])+1; if (srt.get(tmp-1) == srt.get(tmp-2)+1) tmp++;
            Long s2 = (query1(n+2)-query1(tmp-1))*a[i]-query2(n+2)+query2(tmp-1);
            ans = ans.add(new BigInteger(s2.toString()));
            update1(m.get(a[i]));
            update2(m.get(a[i]),a[i]);
        }
        System.out.println(ans.toString());
    }
    static void update1(int idx) {for (;idx <= 200003;idx += idx&-idx) t1[idx]++;}
    static void update2(int idx,int val) {for (;idx <= 200003;idx += idx&-idx) t2[idx] += val;}
    static long query1(int idx) {int tot = 0; for (;idx > 0;idx -= idx&-idx) tot += t1[idx]; return tot;}
    static long query2(int idx) {long tot = 0; for (;idx > 0;idx -= idx&-idx) tot += t2[idx]; return tot;}
}