#include <stdio.h>
#include <cstring>
#include <bitset>
#include <string>
#include <algorithm>
#include <vector>
#include <cmath>
#include <stack>
#include <queue>
#include <list>
#include <set>
#include <stdlib.h>
#include <time.h>
#include <deque>
#define nmax 10000010
using namespace std;
int n,i,j;
long long sol[nmax];
int main(){
freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
scanf("%d",&n);
for (i=1;i<=n;i++) sol[i]=i;
for (i=2;i<=n;i++)
if (sol[i]==i) {
    for (j=i;j<=n;j+=i)
        sol[j]=(sol[j]/i)*(i-1);
}
sol[1]=1;
for (i=2;i<=n;i++)
    sol[i]=2*sol[i]+sol[i-1];
printf("%lld\n",sol[n]);
return 0;
}