#include<bits/stdc++.h> 
using namespace std;
typedef long long ll;
template<typename T1,typename T2> bool chmin(T1 &a,T2 b){if(a<=b)return 0; a=b; return 1;}
template<typename T1,typename T2> bool chmax(T1 &a,T2 b){if(a>=b)return 0; a=b; return 1;}
int dx[4]={0,1,-1,0};
int dy[4]={1,0,0,-1};
long double eps = 1e-6;
long double pi = acos(-1);


signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(20);

    ll n;
    cin>>n;
    ll ans = 0;
    for(ll i=0;i<n;i++){
        ll a; cin>>a;
        ans += a * (i+1) * (n-i);
    }
    cout << ans << endl;
}