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

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import java.io.*;
import java.util.StringTokenizer;


public class Main {

    public static void main(String[] args){
        FastReader fr = new FastReader();
        PrintWriter out = new PrintWriter(System.out);
        int n = fr.nextInt() , counter = 0;
        if (n < 4) {
            System.out.println("0");
            return;
        }
        for (int i = 2; i <= n; i ++){
            int f = n / i;
            if (n / i > 1) {
                counter += 4 * (((f * (f + 1)) / 2) - 1);
            }
        }

        out.print(counter);
        out.close();
    }






    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }

    public static final int MAX_INT = Integer.MAX_VALUE;
    public static final int MIN_INT = Integer.MIN_VALUE;
    public static final long MAX_LONG = Long.MAX_VALUE;
    public static final long MIN_LONG = Long.MIN_VALUE;
    public static final int EPSILON = 1000000007;
    public static final int BIG_9 = 1000000000;
    public static final int BIG_5 = 100000;
    public static final double SMALL_9 = 0.000000001;
    public static final double SMALL_5 = 0.00001;

}
