#include <bits/stdc++.h>
#define rep(i,n)for(int i=0;i<(n);i++)
#define EPS (1e-9)
using namespace std;

double dp[500][1<<6];
int main(){
	int n;scanf("%d",&n);
	dp[0][0]=1;
	rep(i,n){
		if(abs(dp[i][(1<<6)-1]-1)<EPS){
			printf("%.12lf\n",1.0);
			return 0;
		}
		rep(j,1<<6){
			if(dp[i][j]==0)continue;
			rep(k,6){
				dp[i+1][j|1<<k]+=dp[i][j]/6;
			}
		}
	}
	printf("%.12lf\n",dp[n][(1<<6)-1]);
}