#include <cstdio>

using namespace std;
int DP[1000005],N;

int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);

    scanf("%d",&N);
    for(int i = 1; i <= N; ++i)
        DP[i] = i-1;
    for(int i = 2; (i<<1) <= N; ++i)
        for(int j = 2; i*j <= N; ++j)
            DP[i*j] -= DP[i];
    long long rez = 0;
    for(int i = 1; i <= N; ++i)
        rez += DP[i];
    rez *= 2;
    printf("%lld\n",rez+1);

    return 0;
}