#include<bits/stdc++.h>
#define int long long 
const int maxn = 2e5 + 5;
const int inf = 1e18;
const int base = 31;
const int mod = 1e9 + 7;
const int mod2 = 1212121;
using namespace std;
int n;
int res = 0;
signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n;
    for(int i = 1; i <= n; i++) {
        int x;
        cin >> x;
        res += x * (n - i + 1) * i;
    }
    cout << res << "\n";
}