#include <bits/stdc++.h>
using namespace std;

int main()
{
	int X;
	cin >> X;

	int ans = 0;
	int x = 0;
	while( 1 ) {
		x += 2;
		ans += 2;
		if( x == X ) break;
		x += 2;
		ans += 2;
		if( x == X ) break;
		x--;
		ans++;
		if( x == X ) break;
		x--;
		ans++;
		if( x == X ) break;
		x += 2;
		ans += 2;
		if( x == X ) break;
		x--;
		ans++;
		if( x == X ) break;
		x--;
		ans++;
		if( x == X ) break;
	}

	cout << ans << endl;
}