#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    //想定TLE3 (O(N^2))
    long long N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++){
        cin >> A[i];
    }
    vector<long long> S(N + 1, 0);
    for (int i = 0; i < N; i++){
        S[i + 1] = S[i] + A[i];
    }
    long long ans = 0;
    for (int i = 0; i < N; i++){
        for (int j = i; j < N; j++){
            ans += S[j + 1] - S[i];
        }
    }
    cout << ans << endl;
}