#include <stdio.h>
#include <stdint.h>


int main (){
long long n;
long long ar[1000001];
freopen( "fractii.in","r",  stdin );
freopen( "fractii.out", "w", stdout);
scanf("%llu", &n) ;

memset(ar, 0, sizeof(long long)* 1000001);
long long sum = 0;
for (long long j = 2; j <=n; ++j){
	ar[j] += j - 1;
	for (long long k = 2*j; k <=n; k+=j){
		ar[k] -= ar[j];
	}
	sum+= ar[j];
}



printf("%llu", 2 *sum + 1);


return 0;
}