#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define mod 1000000007ll
#define loop(i, n) for (int i = 0; i < n; i++)
#define all(v) v.begin(), v.end()
#define putout(a) cout << a << '\n'
#define Sum(v) accumulate(all(v), 0ll)

int main()
{
    ll N, a, ans = 0;
    cin >> N;
    loop(i, N)
    {
        cin >> a;
        ans += a * (1 + i) * (N - i);
    }
    putout(ans);
    return 0;
}