#include <bits/stdc++.h>
using namespace std;
typedef long long int lli;

int main() {

    lli N; cin >> N;
    lli sum = N * (N + 1) / 2;
    lli ans = sum;
    for (int i = N; i >= 1; i--) {
        sum -= 2 * N;
        ans = min (ans, abs(sum));
    }

    cout << ans + 15 << "\n";

    return 0;
}