#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int N;
LL A[200000];

int main() {
    cin >> N;
    rep(i, N) cin >> A[i];

    LL ans = 0;
    rep(i, N) ans += A[i] * (i + 1) * (N - i);
    cout << ans << endl;

    return 0;
}