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

public class MainClass
{
    public static void main(String[] args)throws IOException
    {
        Reader in = new Reader();
        int n = in.nextInt();
        DSU DSU = new DSU(n + 1);
        for (int i=0;i<=n;i++)   DSU.makeSet(i);
        for (int i=2;i<=n;i++)
        {
            for (int j=2 * i;j<=n;j+=i)
            {
                long div = (long)j / i;
                DSU.unionSets(i, j, div);
            }
        }
        long max = Long.MIN_VALUE;
        HashSet<Integer> h = new HashSet<>();
        for (int i=2;i<=n;i++)
        {
            int x = DSU.findSet(i);
            if (h.contains(x))
                continue;
            else
            {
                long ans = 4L * DSU.sum[x];
                max = Math.max(max, ans);
            }
        }
        System.out.println(max);
    }
}
class DSU
{
    int[] parent;
    int[] size;
    long[] sum;
    //Pass number of total nodes as parameter to the constructor
    DSU(int n)
    {
        this.parent = new int[n];
        this.size = new int[n];
        this.sum = new long[n];
        Arrays.fill(parent, -1);
    }

    public void makeSet(int v)
    {
        parent[v] = v;
        size[v] = 1;
    }

    public int findSet(int v)
    {
        if (v == parent[v]) return v;
        return parent[v] = findSet(parent[v]);
    }

    public void unionSets(int a, int b, long s)
    {
        a = findSet(a);
        b = findSet(b);
        if (a != b)
        {
            if (size[a] < size[b])
            {
                int temp = a;
                a = b;
                b = temp;
            }
            parent[b] = a;
            size[a] += size[b];
            sum[a] += sum[b] + s;
        }
    }
}
class Reader
{
    final private int BUFFER_SIZE = 1 << 16;
    private final DataInputStream din;
    private final byte[] buffer;
    private int bufferPointer, bytesRead;

    public Reader()
    {
        din = new DataInputStream(System.in);
        buffer = new byte[BUFFER_SIZE];
        bufferPointer = bytesRead = 0;
    }

    public Reader(String file_name) throws IOException
    {
        din = new DataInputStream(new FileInputStream(file_name));
        buffer = new byte[BUFFER_SIZE];
        bufferPointer = bytesRead = 0;
    }

    public String readLine() throws IOException
    {
        byte[] buf = new byte[64]; // line length
        int cnt = 0, c;
        while ((c = read()) != -1)
        {
            if (c == '\n')
                break;
            buf[cnt++] = (byte) c;
        }
        return new String(buf, 0, cnt);
    }

    public int nextInt() throws IOException
    {
        int ret = 0;
        byte c = read();
        while (c <= ' ')
            c = read();
        boolean neg = (c == '-');
        if (neg)
            c = read();
        do
        {
            ret = ret * 10 + c - '0';
        }  while ((c = read()) >= '0' && c <= '9');

        if (neg)
            return -ret;
        return ret;
    }

    public long nextLong() throws IOException
    {
        long ret = 0;
        byte c = read();
        while (c <= ' ')
            c = read();
        boolean neg = (c == '-');
        if (neg)
            c = read();
        do {
            ret = ret * 10 + c - '0';
        }
        while ((c = read()) >= '0' && c <= '9');
        if (neg)
            return -ret;
        return ret;
    }

    public double nextDouble() throws IOException
    {
        double ret = 0, div = 1;
        byte c = read();
        while (c <= ' ')
            c = read();
        boolean neg = (c == '-');
        if (neg)
            c = read();

        do {
            ret = ret * 10 + c - '0';
        }
        while ((c = read()) >= '0' && c <= '9');

        if (c == '.')
        {
            while ((c = read()) >= '0' && c <= '9')
            {
                ret += (c - '0') / (div *= 10);
            }
        }

        if (neg)
            return -ret;
        return ret;
    }

    private void fillBuffer() throws IOException
    {
        bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
        if (bytesRead == -1)
            buffer[0] = -1;
    }

    private byte read() throws IOException
    {
        if (bufferPointer == bytesRead)
            fillBuffer();
        return buffer[bufferPointer++];
    }

    public void close() throws IOException
    {
        if (din == null)
            return;
        din.close();
    }
}