#include <bits/stdc++.h>
using namespace std;
int a[105];
long long ans = 0;
int main() {
  cin >> a[0];
  for (int i = 1; i <= a[0]; ++i) {
    cin >> a[i];
    ans += a[i] * i;
  }
  cout << ans << endl;
  return 0;
}
