#include <iostream>
#include <utility>
#include <algorithm>

using namespace std;

int main() {
    int n,k;
    cin >> n >> k;
    double ans = n/2.0 ;
    cout << ans << endl;
}

/*
項数*(初項+末項)/2
* 1/(n+1)*k
* 0*k * (1/(n+1)*k) + 1*k ...
* 0 * (1/(n+1)) + 1 * (1/(n+1)) + 2 
* 1からNまでの和 / (n+1)
*/