#include <iostream>
#include <vector>
#include <set>
#include <queue>
#include <algorithm>
#include <string>
#include <fstream>
#include <cctype>
#include <iomanip>
#include <cmath>
#include <cstring>
#include <map>
#include <bitset>
#include <stack>
/*  //c++11
#include <unordered_map>
#include <unordered_set>
#include <tuple>
*/

using namespace std;

//ifstream fin("1.in");
//ofstream fout("1.out");

int solve()
{
    int n;
    cin>>n;
    if(n == 2)
        return 1;
    if(n == 3)
        return 2;
    if(n == 4)
        return 2;
    for(int i = 2; i <= sqrt(n); i++)
        if(n%i ==0)
            return 0;
    return n-1;

}

int main()
{
    //freopen("1.in","r",stdin);
    //freopen("1.out","w",stdout);
    cout<<solve();
    return 0;
}


//FILE!!!