#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define maxn 200005

int n;
int a[maxn];
ll sum;

int main()
{
   

    cin >> n;

    sum = 0;

    for (int i = 1; i <= n; i++) cin >> a[i];

    for (int i = 1; i <= n; i++){
        sum += (ll)(1LL*a[i]*i*(n-i+1));
    }

    cout << sum;

    return 0;
}