#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("inversmodular.in");
ofstream fout("inversmodular.out");
/*int fi(int n)
{
    int f=1, a, p;
    for (p=2; p*p<=n; p++){
        if (n%p==0){

        }
    }
    return f;
}*/
int main()
{
    /*int n;
    cin>>n;
    cout<<fi(n);*/
    int a, n;
    fin>>a>>n;
    fout<<a-2;
    return 0;
}