#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    int n;
    n=k*(k+1);
    n=n/2;
    int arr[n],sum=0;
    int i=0,j;
        for(j=1;j<=10000000;j++)
        {
            if(j%2==1)
            {
               arr[i]=j;
                sum=sum+arr[i];
                i++;
                if(i==n)
                {
                    break;
                }
            }
        }
    n=(k-1)*k;
    n=n/2;
    int sum1=0;
    for(i=0;i<n;i++)
    {
        sum1=sum1+arr[i];
    }
    return(sum-sum1);
    
    
}

int main() {
    int k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}