import java.util.*;
public class Solution {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int k = in.nextInt();
        int[] a = new int[10000000];
        int q=0, n=1, w=0, sum=0;
        for(int i=1;i<20000000;i++){
            if(i%2!=0){
                a[q]=i;
                q++;
            }
        }
        while(n<k){
            for(int i=1;i<=n;i++){
                sum+=a[w];
                //System.out.println(sum);
                w++;
            }
            n++;
        }
        sum=0;
        for(int i=0;i<=k;i++){
            //System.out.println(sum);
            sum+=a[w];
            
        }
        System.out.println(sum-1);
    }
}