#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
	const double PI=acos(-1.0);
	const double Z=PI*PI/6.0;
	int n; cin>>n;
	double p=1;
	for(int i=0; i<n; i++) p*=Z;
	p/=n;
	cout<<(ll)p<<endl;
	return 0;
}