#include <bits/stdc++.h>
int main() {
  int n, num;
  int i;
  while (scanf("%d", &n) != EOF) {
    int res = 0;
    for (i = 0; i < n; ++i) {
      scanf("%d", &num);
      res += (i + 1) * num;
    }
    printf("%d\n", res);
  }
  return 0;
}
