#include<stdio.h>
#define NRMAX 1000010

long long v[NRMAX];

int main()
{
    FILE *f, *g;

    long long n,rez=0,i,j;

    f=fopen("fractii.in","r");
    g=fopen("fractii.out","w");

    fscanf(f,"%lld",&n);

    for(i=2;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)
    for(j=2*i;j<=n;j+=i)
        v[j]-=v[i];

    for(i=2;i<=n;i++)
        rez=rez+v[i];

    fprintf(g,"%lld",rez*2+1);

    fclose(f);
    fclose(g);

    return 0;
}