#include <iostream>
#include <vector>
using namespace std;
using ll = long long int;

int main(){
    int n;
    cin >> n;
    vector<ll> a(n);
    for(auto &p: a) cin >> p;

    ll ans = 0;
    for(int i = 0; i < n; i++){
        ans += a[i] * (i+1) * (n-i);
        //cerr << a[i] * (i+1) * (n-i) << " ";
    }
    cout << ans << endl;
    return 0;
}