#include<fstream>
#define dim 15000007
using namespace std;


ifstream f("12perm.in");
ofstream g("12perm.out");
long long  T[dim],n,i;
int main (){
	
	f>>n;
	T[1] = 1, T[2] = 2, T[3] = 6, T[4] = 12;
	if(n>4){
		
		for(i=5;i<=n;++i)
			T[n]=T[i-1]+T[i-3]+2*(i-2);
		
		g<<T[n]<<"\n";
	}
	else
		g<<T[n]<<"\n";
	
	return 0;
}