#include <stdio.h>
#include <stdlib.h>

int phi[1000010];
int main()
{
    FILE*fin=fopen("fractii.in","r");
    FILE*fout=fopen("fractii.out","w");
    int n,a,b;
    long long nr;
    fscanf(fin,"%d",&n);
    for(a=1;a<=n;a++)
        phi[a]=a-1;
    for(a=2;a<=n;a++)
        for(b=a*2;b<=n;b+=a)
            phi[b]-=phi[a];
    for(a=2,nr=0;a<=n;a++)
        nr+=phi[a];
    fprintf(fout,"%ld",2*nr+1);
    fclose(fin);
    fclose(fout);
    return 0;
}