#include<iostream>
#include<cstdio>
#include<vector>
#include<queue>
#include<map>
#include<string>
#include<algorithm>
#include<functional>
using namespace std;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define INF 1<<30
#define MP make_pair
#define mp make_pair
#define pb push_back
#define PB push_back
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define ll long long
#define ull unsigned long long

ll cmp(int n,int r){
	ll ans=1;
	REP(i,r){ ans*=n-i;}
	REP(i,r){ans/=i+1;}
	return ans;
}
int main(){
	int n;cin>>n;
	double ans=(double)cmp(n,5)/(double)cmp(99,5)*12.0;
	printf("%.20f\n",ans);
	return 0;
}