#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
typedef long long ll;
using namespace std;

int main() {
    ll N;
    cin >> N;

    ll ans = 1;
    if (N % 2 == 0) {
        ans = 2 + N / 2 - 1;
    }
    cout << ans << endl;

    return 0;
}