#include<stdio.h>
long long x[1000001], i,j;
int n;
int main(){
    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);

    scanf("%d", &n);

    for(i=1; i<=n; ++i)
        x[i]=i-1;

    for(i=2; i<=n; ++i)
        for(j=2*i; j<=n; j+=i)
            x[j]-=x[i];

    j=0;
    for(i=2; i<=n; i++)
        j+=x[i];

    j=j*2+1;

    printf("%lld", j);

    fclose(stdin);
    fclose(stdout);
    return 0;
}