#include <bits/stdc++.h>

using ll = long long;

using namespace std;

int main()
{
    ll n,t{ 0 };
    scanf("%lld", &n);

    for (ll i = 0; i < n; ++i)
    {
        ll a;
        scanf("%lld", &a);
        t += a*(n-i)*(i+1);
    }

    printf("%lld\n", t);
    return 0;
}