#include <stdio.h>
#include <stdint.h>
 
 
int main (){
int n;
int ar[1000001];
freopen( "fractii.in","r",  stdin );
freopen( "fractii.out", "w", stdout);
scanf("%d", &n) ;
 
 
for (int  i = 2 ; i <= n; ++i)
    ar[i] = i - 1;
long long sum = 0;
for (int j = 2; j <=n; ++j){
    for (int k = 2*j; k <=n; k+=j){
        ar[k] -= ar[j];
    }
    sum+= ar[j];
}
 
 
 
printf("%llu", 2 *sum + 1);
 
 
return 0;
}