#include <bits/stdc++.h>
using namespace std;
long long a[105], ans, n;
int main() {
  scanf("%lld", &n);
  for (long long i = 1; i <= n; i++) {
    scanf("%lld", &a[i]);
    ans += a[i] * i;
  }
  printf("%lld\n", ans);
  return 0;
}
