use proconio::input;

fn solve() -> u64 {
  input! {
    n: u64,
  }
  let primes = eratosthenes(200000);
  let mut ans = 0;
  for &p in &primes {
    let p = p as u64;
    let mut x = p * p;
    while x <= n {
      ans += x;
      x = x.saturating_mul(p);
    }
  }
  ans
}

fn main() {
  let ans = solve();
  println!("{}", ans);
}

fn eratosthenes(n: usize) -> Vec<usize> {
  let mut arr = vec![true; n + 1];
  arr[0] = false;
  arr[1] = false;
  let mut i = 2;
  while i * i <= n {
    if arr[i] {
      for x in i..=(n / i) {
        arr[i * x] = false;
      }
    }
    i += 1;
  }
  let mut primes = Vec::new();
  for j in 0..=n {
    if arr[j] {
      primes.push(j);
    }
  }
  primes
}