#include<bits/stdc++.h>
#define LL long long
using namespace std;
int main()
{
    LL n;scanf("%lld", &n);
    LL ans=0;
    for(LL l=1, r; l <= n; l = r + 1)
    {
        r = n / (n / l);
        ans += (n / l) * (r - l + 1);
    }
    printf("%lld\n", ans);
    return 0;
}