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

#define reep(i,a,b) for(int i=(a);i<(b);i++)
#define rep(i,n) reep((i),0,(n))

int main(){
	int n;
	cin>>n;
	double c[110][110];
	rep(i,110) rep(j,110) c[i][j]=0;
	rep(i,110){
		c[i][0]=c[i][i]=1;
		rep(j,i){
			c[i][j+1]=c[i-1][j+1]+c[i-1][j];
		}
	}
	if(n<5){
		cout<<0<<endl;
	}
	else{
		cout<<fixed<<setprecision(20)<<c[n][5]/c[99][5]*12<<endl;
	}
}