#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define fi first
#define se second
#define pb push_back
#define sz size()
#define faster() ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
#define vi vector<int>
#define vll vector<ll>
#define vs vector<string>
#define PI 3.141592653589793238
//C:\Users\Public\cpp_learning\input.txt
int main()
{
    int n; cin >> n;
    double s = 0;
    for (double i=0; i<n; i++)
    {
        s += ((2*i+1)/(2*i+2));
    }
    cout << s;
    return 0;
}
 

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