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
//make sure to make new file!
import java.io.*;
import java.util.*;
//race against danny solving a rubik's cube
public class D520{
   
   public static void main(String[] args)throws IOException{
      BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
      PrintWriter out = new PrintWriter(System.out);
      
      int n = Integer.parseInt(f.readLine());

      int N = 100005;
      
      long[] answer = new long[N];
      
      answer[2] = 0L;
      
      for(int k = 3; k < N; k++){
         answer[k] += answer[k-1];
         
         //get factors
         for(int j = 2; j*j <= k; j++){
            if(k%j == 0){
               answer[k] += k/j;
               if(j*j != k)
                  answer[k] += j;
            }
         }
      }
      
      out.println(answer[n]*4);
         
      
      

      
      
      
      
      
      out.close();
   }
   
      
}