#include<stdio.h>
FILE *f=fopen("fractii.in","r"), *g=fopen("fractii.out","w");

long int n, i, j, v[1000005];
long long int suma=0;

int main(){

    fscanf(f,"%ld\n",&n); fclose(f);

    for(i=1;i<=n;i++){v[i]=i-1;}

    for(i=2;i<=n;i++){
        for(j=2*i;j<=n;j+=i){
            v[j]=v[j]-v[i];
        }
    }
    for(i=2;i<=n;i++){suma+=v[i];}

    fprintf(g,"%lld\n",2*suma+1);
    fclose(g);

return 0;
}