#include<stdio.h>    

//#define MAX 1000010;
const long MAX=1000010;    
int main(){
    long long int n,rez=0,i,j,k,l;
    long long iter[MAX];
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%lld",&n);
    for(i=1;i<=n;++i)
            iter[i]=i-1;
    for(j=2;j<=n;++j)
                     for(l=2*j;l<=n;l+=j)
                                         iter[l]-=iter[j];
    for(k=2;k<=n;k++)
            rez+=iter[k];
    printf("%lld",2*rez+1);
    //printf("%d %d",sizeof(long),sizeof(long long));
    return 0;
}