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 sys
import math
input = sys.stdin.readline
from functools import cmp_to_key;

def pi():
    return(int(input()))
def pl():
    return(int(input(), 16))
def ti():
    return(list(map(int,input().split())))
def ts():
    s = input()
    return(list(s[:len(s) - 1]))
def invr():
    return(map(int,input().split()))
f = [];
def factMod(n,m):
    global f;
    f = [1 for i in range(n+1)];
    f[0] = 1;
    for i in range(1,n+1):
        f[i] = (f[i-1]*i)%m;

def fact(n):
    global f;
    f = [1 for i in range(n)];
    for i in range(1,n):
        f[i] = f[i-1]*i;

def fast_mod_exp(a,b,m):
    res = 1;
    while b > 0:
        if b & 1:
            res = (res*a)%m;
        a = (a*a)%m;
        b = b >> 1;
    return res;

def inverseMod(n,m):
    return fast_mod_exp(n,m-2,m);

def ncrMod(n,r,m):
    if r == 0: return 1;
    if n < r: return 0;
    return ((f[n]*inverseMod(f[n-r],m))%m*inverseMod(f[r],m))%m;

def ncr(n,r):
    if r == 0: return 1;
    if n < r: return 0;
    return (f[n])/(f[r]*f[n-r]);
def nc2(n):
    return (n*(n-1))/2;

def main():
    D();

def D():
    n = pi();
    ans = 0;
    for i in range(2,n):
        ans += 4*i*(math.floor(n/i)-1);
    print(ans);
    
main();