#include <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>
#include <cassert>

#include <algorithm>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <cmath>
#include <numeric>
#include <bitset>

#include <cstdio>
#include <cstring>

using namespace std;

#define rep(i, n) for (int i = 0, _n = (int)(n); i < _n; i++)
#define fer(i, x, n) for (int i = (int)(x), _n = (int)(n); i < _n; i++)

////////////////////////////////////////////////////////////////////////////////
const int N = 1000000;
double f[N];
void init(){
    f[1]=1;
    fer(i,2,N+1) f[i] = f[i-1] + 1.0/i;
}
int main()
{
    //freopen("in.txt","r",stdin);
    ios_base::sync_with_stdio(0);
    int n;
    init();
    while(scanf("%d",&n)!=EOF){
        printf("%.4lf\n",    n > N ? 0.57721566490153286060651209+log(n+0.0) : f[n]     );
    }
    return 0;
}