#include<stdio.h>
#include<stdlib.h>
int main(){
    FILE *f,*g;
    f = fopen("fractii.in","r");
    g = fopen("fractii.out","w");
    long n;
    long long sum = 0;
    fscanf(f,"%ld",&n);
    long a[n+1];
    long i,j;
    for (i=2;i<=n;i++)
        a[i]=i-1;

    for (i=2;i<=n;i++)
    {
        sum+=a[i];
        for (j=2*i;j<=n;j+=i)
            a[j]-=a[i];
    }
    fprintf(g,"%lld",2*sum+1);
    fclose(g);
    fclose(f);
}