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

int main(){
    FILE *in, *out;
    in = fopen("fractii.in", "r");
    out = fopen("fractii.out", "w");
    int n, i, j;
    long long f = 0;
    fscanf(in, "%d", &n);
    int p[n];
    	
    for (i = 1; i <= n; i++)
	p[i] = i - 1;

    for ( i = 2; i <= n; i++)
	for (j = 2 * i; j <= n; j +=i)
	    p[j] -= p[i];
    for (i = 2; i <=n; i++)
	f += p[i];
    fprintf(out,"%lld", 2 * f + 1);
    fclose(in);
    fclose(out);    
    return 0;
}