#include <stdio.h>

int main() {
    int v[500000],n,s=0,i,j;
    FILE *f;
    f=fopen("fractii.in","r"); fscanf(f,"%d",&n); fclose(f);
    for (i=1; i<=n; i++) v[i]=i-1;
    for (i=2; i<= (int) n/2; i++) {
        j=2;
        while (i*j<=n) { v[i*j]=v[i*j]-v[i]; j++; }
    }
    for (i=1; i<=n; i++) s=s+v[i];
    s=s*2+1;
    f=fopen("fractii.out","w"); fprintf(f,"%d",s); fclose(f);
    return 0;
}