#include <iostream>
using namespace std;
#define N 1000002
int fi[N],s[N];
int main()
{
    int n,i,j;
    cin>>n;
    for(i=1;i<=N;i++) fi[i]=i-1;
    for(i=2;i<=N;i++){
        for(j=2*i;j<=N;j=j+i) fi[j]=fi[j]-fi[i];
    }
    for(i=1;i<=N;i++) s[i]=s[i-1]+fi[i];
    cout<<2*s[n]+1;
    return 0;
}