#include<iostream>
#include<cmath>
#include<vector>
#include<stack>
#include<queue>
#include<set>
#include<algorithm>
#include<string>

#define x first
#define y second
#define SP system("pause")

using namespace std;

int main()
{
    int n, k;

    cin >> n;

    cout << n / 2 << endl;

    return 0;
}