#include <stdio.h>

int i, n, v[100], j, nr;

void cit()
{
        FILE *f=fopen("fractii.in", "r");
        fscanf(f, "%d", &n);
        fclose(f);
}

void tip()
{
        FILE *f=fopen("fractii.out", "w");
        fprintf(f, "%d\n", nr);
        fclose(f);
}

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

int main()
{
        cit();
        fct();
        tip();
        return 0;
}