#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)

using namespace std;
using ll = long long;

int main() {
    int n;
    cin >> n;
    
    vector<int> a(n);
    rep(i, n) cin >> a[i];
    
    ll ans = 0;
    rep(i, n) {
        ans += (ll)a[i]*(i+1)*(n-i);
    }
    
    cout << ans << '\n';
    
    return 0;
}