//last dance go go
#include<bits/stdc++.h>
using namespace std;


#define NAME "unknown"
#define int int64_t
#define fi first
#define se second
#define ii pair<int,int>
#define iii pair<ii,int>
#define pb push_back
#define endl "\n"
#define ios; ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

const int N = 1e5 + 5;

int a[N], f[N];

vector<int> v;

signed main() {
    ios;

     if(ifstream (NAME".inp"))
    {
    freopen(NAME".inp","r",stdin);
   freopen(NAME".out","w",stdout);
    }
    int n;
    cin >> n;
    int ans = 0;
    for(int i = 1;i<=n;i++)
    {
        int x;
        cin >> x;
        ans += x * i * (n - i + 1);
    }
    cout << ans;
    return 0;
}