#include <bits/stdc++.h>
using namespace std;
long long MOD = 1000000007;
int MAX_N = 200000;
int MAX_A = 1000000;
int main(){
    long long N;
    cin >> N;
    assert(N >= 1);
    assert(N <= MAX_N);
    vector<long long> A(N);
    for (int i = 0; i < N; i++){
        cin >> A[i];
        assert(A[i] >= 0);
        assert(A[i] <= MAX_A);
    }
    long long ans = 0;
    for (long long i = 0; i < N; i++){
        long long M = (i + 1) * (N - i);
        ans = ans + A[i] * M;
    }
    cout << ans << endl;
}