#include<stdio.h>

int main()
{
    FILE *fin,*fout;
    long n,i,j,s=0;
    long v[1000001];

    fin=fopen("fractii.in","rt");
    fscanf(fin,"%ld",&n);
    fclose(fin);

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

    s=s*2+1;
    fout=fopen("fractii.out","wt");
    fprintf(fout,"%ld",s);
    fclose(fout);



    return 0;
}