#include <bits/stdc++.h>
using namespace std;
const int N = 106;
int n, a[N];
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  long long ans = 0;
  for (int i = 1; i <= n; i++) ans += i * a[i];
  cout << ans << endl;
  return 0;
}
