#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 0;
  char ch = getchar();
  while (!isdigit(ch)) f |= ch == '-', ch = getchar();
  while (isdigit(ch)) x = x * 10 + (ch ^ 48), ch = getchar();
  return f ? -x : x;
}
int main() {
  int n = read(), ans = 0;
  for (int i = 1; i <= n; ++i) ans += read() * i;
  printf("%d\n", ans);
  return 0;
}
