#include<bits/stdc++.h>
/*
    --> Programmed by katamori1310 <--
                ???
    Chillin with Blue Archive 
*/
#define int long long
#define ull unsigned long long
#define fi first
#define se second
#define aris ""
using namespace std;
const int MAXN = 100000;
const int MOD = 1e9 + 7;
const int MAXP = 1e6;
const int INF = 1e18;
const int MODE = MOD - 2;

/* 
    I love Aris and Kei at the same time
        ? ? ? Pampakapam ? ? ?
*/
inline void kei(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}
int n;
int a[2 * MAXN + 5];
int pfs[2 * MAXN + 5];
void solve(){
    cin >> n;
    int res = 0;
    for(int i = 1; i <= n; ++i) {
        int a;
        cin >> a;
        res += a * i * (n - i + 1);
    }
    cout << res << "\n";
}
signed main(){
    if(fopen(aris".inp", "r")){
        freopen(aris".inp", "r", stdin);
        freopen(aris".out", "w", stdout);
    }
    kei();
    int T;
    // cin >> T;
    T = 1;
    while(T--){
        solve();
    }
    return 0;
}

// ???