#include<cstdio>
using namespace std;
const int LIM=1000010; int n;
long long v[LIM], sol=0;
int main(){
    FILE *in=fopen("fractii.in","r"), *out=fopen("fractii.out","w");
    int n;
    fscanf(in, "%d\n", &n);
    for(int i=2; i<=n; i++)
        v[i]=i-1;
    for(int i=2; i<=n; i++){
        for(int j=2*i; j<=n; j+=i)
            v[j]-=v[i];
        sol+=2*v[i];
    }
    fprintf(out, "%lld\n", sol+1);
    return 0;
}