#include <iostream>
#include <vector>
#include <string>
#include <cmath>
using namespace std;
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int x;
    cin >> x;
    double ans = 0;
    long long INF = 1e15;
    vector<vector<long long>> vec(100000, vector<long long> (200, -1));
    for(int i = 2; i < 100000; i++){
        vec[i][0] = 1;
        for(int j = 1; j < 200; j++){
            if(INF / (long long)i < vec[i][j - 1]){
                vec[i][j] = -1;
                break;
            }
            else vec[i][j] = vec[i][j - 1] * (long long)i;
        }
    }
    for(int i = x; i < 200; i++){
        for(int j = 2; j < 100000; j++){
            if(vec[j][i] == -1) break;
            ans += 1 / (double)vec[j][i] * 1e6;
        }
    }
    long long t = ans;
    cout << t << endl;
}