#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <string>
#include <set>
#include <cstdint>
#include <numeric>
#define INF 1000000000
#define LLINF 2000000000000000
#define MOD 1000000007
using namespace std;
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define LOOP(i,N) for(int i=0;i<N;i++)
#define LOOP1(i,N) for(int i=1;i<=N;i++)
typedef pair<int,int> P;
typedef pair<int,pair<int,int> > PP;
#define int long long

signed main(){
  int n;
  cin >> n;
  double e[n+2];
  e[0] = 1;
  double ans = 0;
  LOOP1(i,n-1){
    //n面の中から n-i を選ぶ回数の期待値
    double p = (double)(n-i)/n;
    e[i] = 1/(p);
    ans += e[i];
    //cerr << e[i] << endl;
  }
  printf("%.12f\n", ans);
}

#include <iostream>

using namespace std;

int main(void)
{
	long long n;
	cin >> n;
	const int x[] = { 2,3,4,5,7,8,9,11,13,16,17,19,23,25,27,29,31};
	const int e[] = { 2,3,2,5,7,2,3,11,13,2,17,19,23,5,3,29,31};
	long long ans = 1;

	for (int i = 0; x[i] <= n; i++) {
		ans *= e[i];
	}
	cout << ans+1 << endl;
	return 0;
}


