#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<utility>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<functional>
#include<math.h>
#include<random>
#include <bitset>
#include <cassert>
#include <complex>
using namespace std;
#define N (1000000000+7)
//#define N 998244353
#define INF 1e16
typedef long long ll;
typedef pair<int,int> P;
const int inf = 1e8;


ll gcd(ll a, ll b) {
	if (b > a) {
		ll tmp = b;
		b = a;
		a = tmp;
	}
	if (a%b == 0)return b;
	else return gcd(b, a%b);
}

int main() {
    int n;
    cin>>n;
    if(n==0)cout<<0<<endl;
    else{
        if(n==1)cout<<0.70000000<<endl;
        else{
            cout<<"0.";
            for(int i=1;i<=n;i++){
                if(i%6==1)cout<<1;
                if(i%6==2)cout<<4;
                if(i%6==3)cout<<2;
                if(i%6==4)cout<<8;
                if(i%6==5)cout<<5;
                if(i%6==0)cout<<7;
            }
            cout<<endl;
        }
    }
}