#include<stdio.h>
int a[1000002];

int main(){

    FILE *fin=fopen("fractii.in","r"),
        *fout=fopen("fractii.out","w");

    int N;
    fscanf(fin,"%d",&N);
    long long nr=0;


    for(int i=1;i<=N;i++) a[i]=i-1;

    for(int i=2;i<=N;i++)
        for(int j=2;(long long)j*i<=N;j++) a[i*j]-=a[i];

    for(int i=2;i<=N;i++) nr+=a[i];

    fprintf(fout,"%lld",1+nr*2);

    fclose(fin);
    fclose(fout);


    return 0;
}