28237
 13190
 39914
 81367
 8554
 61106
 67448
 39004
 22308
 16054
 71468
 60501
 100
 300
 59632
 90783
 5611
 1000
 69475
 69753
 10
 5
 582
 8
 36961
 5071
 20
 53213
 92775
 28738
 100000
 92280
 37944
 9
 2627
 7
 3

1028306548 224346172 2054738392 8539207488 94344524 4816051228 5867563092 1962150044 641839188 332342852 6587875268 4721174212 12600 115440 4586497300 10630118936 40580456 1286328 6225539588 6275533596 92 8 434692 52 1762017168 33141852 440 3652070664 11101694484 1065137992 12898363344 10983871880 1856988304 64 8885348 28 0
import java.util.*;
import java.math.*;
import java.io.*;

public class CF1062D {
	// A Josh/Billy Collab (mostly Josh)
	final int MAX = 111111;
	public CF1062D() {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		List<Integer> primes = new ArrayList<>();
		boolean[] isPrime = new boolean[MAX];
		Arrays.fill(isPrime, true);
		isPrime[0] = isPrime[1] = false;
		for(int i = 2 ; i < MAX ; i++) {
			if(isPrime[i]) {
				primes.add(i);
				for(int j = i + i ; j < MAX ; j += i)
					isPrime[j] = false;
			}
		}
		long res = 0;
		boolean[] visited = new boolean[MAX];
		for(int prime : primes) {
			if(prime > n) break;
			if(prime <= n / 2 && prime != 2) res += 8;
			for(int i = prime * 2 ; i <= n ; i += prime) {
				if(visited[i]) continue;
				visited[i] = true;
				res += 4 * (i / prime);
			}
		}
		System.out.println(res);
	}
	public static void main(String[] args) { new CF1062D(); }
}
