#include <bits/stdc++.h>
const long long mod = (long long)1e9 + 7;
const long long BASE = 47;
const long long inf = (long long)1e18;
const long double e = 2.718281828459;
const long double pi = 3.141592653;
const long double EPS = 1e-9;
using namespace std;
template <class T>
istream &operator>>(istream &in, vector<T> &arr) {
  for (T &cnt : arr) {
    in >> cnt;
  }
  return in;
};
void solve() {
  long long n;
  cin >> n;
  vector<long long> arr;
  for (int i = 0; i < n; i++) {
    long long x;
    cin >> x;
    if (arr.empty() or arr.back() != x) {
      arr.push_back(x);
    }
  }
  vector<long long> inter(n + 1), have(n + 1);
  for (int i = 0; i < arr.size(); i++) {
    have[arr[i]]++;
  }
  for (int i = 1; i < arr.size(); i++) {
    long long a = arr[i], b = arr[i - 1];
    if (a > b) {
      swap(a, b);
    }
    inter[b] += a;
  }
  vector<long long> dp(n + 1);
  for (int i = 1; i <= n; i++) {
    dp[i] = dp[i - 1] + have[i] * i;
    dp[i] -= inter[i];
  }
  cout << accumulate(dp.begin(), dp.end(), 0LL);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout.precision(30);
  long long seed = time(0);
  cerr << "Seed: " << seed << "\n";
  srand(seed);
  solve();
  return 0;
}
