#include <bits/stdc++.h>
using namespace std;
const int sz = 1e5 + 1;
int b[sz];
vector<int> nn;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, el;
  long long ans = 0;
  long long cur_ans = 0;
  cin >> n;
  vector<pair<int, int>> v;
  for (int i = 0; i < n; i++) {
    cin >> el;
    if (nn.size() == 0 || nn.back() != el) nn.push_back(el);
  }
  int n2 = nn.size();
  int pos = 0;
  for (int i = 0; i < n2; i++) {
    b[i] = nn[i];
    v.push_back({nn[i], i});
  }
  sort(v.begin(), v.end());
  if (n2 == 1) {
    cout << (long long)v[0].first * (n - v[0].first + 1);
    return 0;
  }
  for (int r = 1; r <= n; r++) {
    while (pos < n2 && v[pos].first == r) {
      int p = v[pos].second;
      if (p == 0) {
        if (b[1] < r) {
          cur_ans += r - b[1];
        } else
          cur_ans += r;
      } else if (p == n2 - 1) {
        if (b[n2 - 2] < r) {
          cur_ans += r - b[n2 - 2];
        } else
          cur_ans += r;
      } else {
        if (b[p - 1] < r && b[p + 1] < r) {
          cur_ans -= min(b[p - 1], b[p + 1]);
          cur_ans += r - max(b[p - 1], b[p + 1]);
        } else if (b[p - 1] < r) {
          cur_ans += r - b[p - 1];
        } else if (b[p + 1] < r) {
          cur_ans += r - b[p + 1];
        } else {
          cur_ans += r;
        }
      }
      pos++;
    }
    ans += cur_ans;
  }
  cout << ans;
  return 0;
}
