#include <iostream>
#include <fstream>
#include <cmath>
#include <iomanip>
#include <vector>
#include <algorithm>

#define maxn 100010

using namespace std;

ifstream fin("test.in");
ofstream fout("test.out");

int main()
{
    int n;
    cin >> n;

    bool ok = 0;

    for (int i = 2; i*i <= n; ++i)
    {
        if (n % i == 0)
        {
            ok = 1;
        }
    }

    if (ok)
    {
        if (n == 4)
            cout << 2;
        else cout << 0;
    }
    else
    {
        cout << n-1;
    }
}