#include <iostream>
#include <vector>
using namespace std;

const int maxN = 100000;
// bool u[maxN];
int a[maxN];
int b[maxN];
int main() {
    int N;
    cin >> N;
    vector<bool> u(N);
    long long total = 0;
    for (int i = 0; i < N; ++i) {
        a[i] = rand() % N;
        b[i] = rand() % N;
    }
    for (int it = 0; it < N; ++it) {
        for (int i = 0; i < N; ++i) {
            int x = a[i];
            u[x] = 1;
        }
        for (int i = 0; i < N; ++i) {
            int x = b[i];
            u[x] = 0;
        }
        for (int i = 0; i < N; ++i) {
            total += u[i];
            u[i] = 0;
        }
    }
    cout << total / N << endl;
    return 0;
}