#include<iostream>

using namespace std;

int peoplenumber;

int search(int sum,int n)

{

int total=1;

for(int i=n+1;i<(peoplenumber-sum+1)/2;i++)

{

total+=search(sum+i,i);

}

return total;

}

int main()

{

cin>>peoplenumber;

cout<<search(0,0)-1;

}