#include <iostream>
using namespace std;
int main(){
	int N;
	cin >> N;
	if (N % 2 == 0){
		int a = N / 2;
		cout << (long long) (a + 1) * (a + 1) - 1 << endl;
	} else {
		int a = N / 2;
		int b = (N + 1) / 2;
		cout << (long long) (a + 1) * (b + 1) - 1 << endl;
	}
}