#include <iostream>

#include <string.h>

#include <stdio.h>

using namespace std;

typedef long long LL;

LL work(LL n)

{

    LL ans = ;

    for(int k = ; k <= n / ; k++)

        ans += (n -  * k) /  + ;

    return ans;

}

int main()

{

    LL n;

    while(cin>>n)

        cout<<work(n)<<endl;

    return ;

}

#include <iostream>

#include <string.h>

#include <stdio.h>

using namespace std;

typedef long long LL;

LL work(LL n)

{

    LL k = n / ;

    LL t = (k + ) * n -  * k * (k + ) / ;

    LL ans = k + ;

    if(k & ) t -= (k + ) / ;

    else if(n & ) t -= (k /  + );

    else t -= k / ;

    t >>= ;

    return ans + t;

}

int main()

{

    LL n;

    while(cin>>n)

        cout << work(n) << endl;

    return ;

}