#include <bits/stdc++.h>
using namespace std;
int a[200];
int read() {
  int s = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    s = s * 10 + int(ch) - '0';
    ch = getchar();
  }
  if (f == -1)
    return -s;
  else
    return s;
}
int main() {
  int n;
  n = read();
  int i;
  for (i = 1; i <= n; i++) {
    a[i] = read();
  }
  unsigned long long ans;
  ans = 0;
  for (i = 1; i <= n; i++) {
    ans += a[i] * i;
  }
  cout << ans << endl;
  return 0;
}
