#include <iostream>
#include <stdio.h>
using namespace std;
int cr[1000001];
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    int n,i,r,j;
    unsigned long long sum=0;
    scanf("%d",&n);
    for(i=1;i<=n;i++) cr[i]=i;
    for(i=1;i<=n;i++) {
        sum+=cr[i];
        r=n/i;
        for(j=2;j<=r;j++)
            ciur[i*j]-=ciur[i];
    }
    /**
    p/q e ireductibila <=> q/p e ireductibila
    scadem fr 1/1
    **/
    cout<<2*sum-1;


    return 0;
}