#include <stdio.h>

inline int gcd(int a,int b)
{
    int r;

    while(r=a%b)
    {
    a=b;
    b=r;
    }
    return b;
}



inline int phi(int n)
{
    int i=1,s=0;
    for(i=1;i<=n;++i)
    {
        if(gcd(i,n)==1)
        ++s;
    }
    return s;
}

inline int farey(int n)
{
    if(n==1)return 2;
    else return farey(n-1)+phi(n);
}

int main()
{
    int n;
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
   scanf("%d",&n);
   printf("%d",2*farey(n)-3);


    return 0;
}