source_code: import static java.util.Arrays.*;
  import static java.lang.Math.*;
  import static java.math.BigInteger.*;
  import java.util.*;
  import java.math.*;
  import java.io.*;
  
  public class Main implements Runnable {
      
  	boolean TEST = System.getProperty("ONLINE_JUDGE") == null;
      
      void solve() throws IOException {
      	int n = nextInt();
      	Pair[] ps = new Pair[n];
      	for (int i = 0; i < n; i++) {
      		ps[i] = new Pair(nextInt(), i + 1);
      	}
      	sort(ps, new Comparator<Pair>() {
      		public int compare(Pair a, Pair b) {
      			return a.x - b.x;
      		}
      	});
      	BigInteger res = find(ps, n);
      	for (int i = 0; i * 2 < n; i++) {
      		Pair t = ps[i];
      		ps[i] = ps[n - i - 1];
      		ps[n - i - 1] = t;
      	}
      	res = res.add(find(ps, n));
      	out.println(res);
      }
      
      BigInteger find(Pair[] ps, int n) {
      	BigInteger res = ZERO;
      	int i = 0;
      	FenwickTree ft = new FenwickTree(n + 1);
      	boolean[] added = new boolean[n + 1];
      	for (int j = 0; j < n; j++) {
      		if (abs(ps[j].x - ps[i].x) <= 1) continue;
      		while (abs(ps[j].x - ps[i].x) > 1) {
      			if (!added[ps[i].i]) ft.add(ps[i].i, 1);
      			added[ps[i].i] = true;
      			i++;
      		}
      		i--;
      		long total = ft.sum(n);
      		long left = ft.sum(ps[j].i - 1);
      		long right = total - left;
      		res = res.add(valueOf(ps[j].x).multiply(valueOf(left)));
      		res = res.add(valueOf(-ps[j].x).multiply(valueOf(right)));
      	}
      	return res;
      }
      
      class Pair implements Comparable<Pair> {
      	int x, i;
      	
      	Pair(int x, int i) {
      		this.x = x;
      		this.i = i;
      	}
      	
      	public int compareTo(Pair p) {
      		return x - p.x;
      	}
      	
      	public String toString() {
      		return "(" + x + ", " + i + ")";
      	}
      }
      
      class FenwickTree {
      	int n;
      	int[] tree;
      			
      	public FenwickTree(int n) {
      		this.n = n;
      		tree = new int[n];
      	}
      			
      	public int sum(int id) {
      		int res = 0;
      		while (id > 0) {
      			res += tree[id];
      			id -= id & -id;
      		}
      		return res;
      	}
      			
      	public void add(int id, int v) {
      		while (id < n) {
      			tree[id] += v;
      			id += id & -id;
      		}
      	}
  
      	int findkth(int k) {
      		int low = 1, high = n;
      		while (low < high) {
      			int mid = (low + high) / 2;
      			int val = sum(mid);
      			if(val < k) low = mid + 1;
      			else high = mid;
      		}
      		return low;
      	}
      }
  
      
      String next() throws IOException {
          while(st == null || !st.hasMoreTokens()) st = new StringTokenizer(input.readLine());
          return st.nextToken();
      }
      
      int nextInt() throws IOException {
          return Integer.parseInt(next());
      }
      
      long nextLong() throws IOException {
          return Long.parseLong(next());
      }
      
      double nextDouble() throws IOException {
          return Double.parseDouble(next());
      }
      
      void debug(Object... o) {
          System.out.println(deepToString(o));
      }
      
      void gcj(Object o) {
          String s = String.valueOf(o);
          out.println("Case #" + test + ": " + s);
          System.out.println("Case #" + test + ": " + s);
      }
      
      BufferedReader input;
      PrintWriter out;
      StringTokenizer st;
      int test;
      
      void init() throws IOException {
          if (TEST) input = new BufferedReader(new FileReader("input.in")); 
          else input = new BufferedReader(new InputStreamReader(System.in));
          out = new PrintWriter(new BufferedOutputStream(System.out));
          //out = new PrintWriter(new BufferedWriter(new FileWriter("output.out")));
      }
      
      public static void main(String[] args) throws IOException {
          new Thread(null, new Main(), "", 1 << 20).start();
      }
      
      public void run() {
          try {
              init();
              if (TEST) {
                  int runs = nextInt();
                  for(int i = 0; i < runs; i++) solve();
              } else solve();
              out.close();        
          } catch (Exception e) {
              e.printStackTrace();
              System.exit(1);
          }
      }
  }