#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using namespace std;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x, to) for (int x = 0; x < (to); x++)
#define REP(x, to) for (int x = 0; x < (to); x++)
#define FORR(x, arr) for (auto &x : arr)
#define FORR2(x, y, arr) for (auto &[x, y] : arr)
#define ALL(a) (a.begin()), (a.end())
#define ZERO(a) memset(a, 0, sizeof(a))
#define MINUS(a) memset(a, 0xff, sizeof(a))
#define MOD 1000000007
#define INF 100000000000001

#define let auto

using i64 = long long;
using ll = long long;
;
using pll = pair<ll, ll>;

#define int long long

template <class T>
bool chmax(T &a, const T &b)
{
  if (a < b)
  {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b)
{
  if (a > b)
  {
    a = b;
    return 1;
  }
  return 0;
}

void solve(void)
{

  int n;
  cin >> n;
  vector<int> vec(n, 0);
  for (int i = 0; i < n; i++)
  {
    cin >> vec[i];
  }
  int res = 0;
  for (int i = 0; i < n; i++)
  {
    int l = i + 1;
    int r = n - i;
    res += vec[i] * r * l;
  }
  cout << res << endl;

  return;
}
int32_t main(int argc, char **argv)
{
  string s;
  int i;
  if (argc == 1)
    ios::sync_with_stdio(false), cin.tie(0);
  FOR(i, argc - 1)
  s += argv[i + 1],
      s += '\n';
  FOR(i, s.size())
  ungetc(s[s.size() - 1 - i], stdin);
  cout.tie(0);
  solve();
  return 0;
}