using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static long sumOfGroup(int k, int[] input, int[] kList) {
        // Return the sum of the elements of the k'th group.
        int kMin = 0;
        int kMax = 0;
        int output = 0;
        for (int i = 0; i < k; i++)
        {
            kMin += kList[i];
        }
        kMax = kMin + k - 1;
        
        
        for (int j = kMin; j <= kMax; j++)
        {
            output += input[j];
        }
        return output;
    }

    static int[] AddToList()
    {
        List<int> list = new List<int>();
        for (int i = 0; i <= 10 * 10 * 10 * 10 * 10 * 10; i++)
        {
            list.Add(i);
        }

        return list.ToArray();
    }
    
    static int[] InitiateInput()
    {
        List<int> list = new List<int>();
        for (int i=0; i < 10*10*10*10*10*10*10; i++)
        {
            if (i % 2 != 0)
            {
                list.Add(i);
            }
        }
        
        return list.ToArray();
    }
    
    static void Main(String[] args) {
        int[] input = InitiateInput();
        int[] kList = AddToList();
        int k = Convert.ToInt32(Console.ReadLine());
        long answer = sumOfGroup(k, input, kList);
        Console.WriteLine(answer);
    }
}