#include <iostream>
#include <cstdio>
#include <cmath>

using namespace std;

int v[1000002];
int nums[1000002];
int obj;
int n;

void inclExcl(int x)
{
    if(nums[x] == 0)
        return;
    int divX = n / x;
    obj -= nums[x] * divX * divX;
    int included = nums[x];
    for(int i = x; i <= n; i += x)
    {
        nums[i] -= included;
    }
}

int main()
{
    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);
    cin >> n;
    for(int i = 1; i <= n; ++i)
        nums[i] = 1;
    obj = n * n;
    for(int i = 2; i <= n; ++i)
    {
        inclExcl(i);
    }
    cout << obj;
    return 0;
}