#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001


int main(){
	
	int n;
	cin>>n;
	
	vector<double> dp(6,0.0);
	dp[0] = 1;
	
	rep(i,n){
		vector<double> ndp(6,0.0);
		rep(j,6){
			int remain = 99 - i;
			if(remain<=0)continue;
			double x = 5-j;
			double y = remain;
			if(j!=5)ndp[j+1] += dp[j] * (x/y);
			ndp[j] += dp[j] * ((y-x)/y);
		}
		swap(dp,ndp);
	}
	
	double t = dp.back();
	//t = 1.0 / t;
	t *= 12;
	cout<<fixed<<setprecision(10)<<t<<endl;
	
	return 0;
}